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RSS Feed for Wolfram Community showing any discussions in tag Wolfram Sciencesearch.php?s=fe9d502914d96ae580a896013a31c1dd sorted by activeIntegrate Tanh(x)*Cos(x) and get rid of the hypergeometric terms?
http://community.wolfram.com/groups/-/m/t/1519418
Hell Everyone , I am solving integration Tanh(x)*Cos(x) shown bellow ,getting hypergeometric terms . How to get rid of it . Thank You
![Hell Everyone , I am solving integration Tanh(x)*Cos(x) shown bellow ,getting hypergeometric terms . How to get rid of it . Thank You][1]
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=integration.png&userId=1301292Sachin V2018-10-18T10:09:25ZIntegrate or DSolve?
http://community.wolfram.com/groups/-/m/t/1520100
Hello folks,
Think of an equation: -g+K*v=D[v]/D[t] and the conditions are when t=0, v=0; where t is time v is velocity, g is a gravitational acceleration and K is some constant. How do you input these on mathematica so it could take the integral of the equation and gives result. I already got the result by hand as follows: v=(g*(1-e^(k*t))/K). whatever I try I cant get this result.
Thanks in advanceNajmiddin Nasyrlayev2018-10-18T14:46:37ZMathematica no longer available for the Raspberry Pi?
http://community.wolfram.com/groups/-/m/t/1511397
EDIT 2: As noted below, the problem is now resolved.
----
EDIT and warning: If you have Mathematica on the Raspberry Pi right now, do not uninstall at this point.
----
Mathematica is no longer included in the Raspbian repositories or the default Raspbian image. The Mathematica and Wolfram Language sections of the Raspberry Pi forum have been purged—apparently gone for good.
I uninstalled it, planning to reinstall a newer version, and it seems that now I lost it permanently.
Are there plans to make it available again?
There's also [a thread about this on the Raspberry Pi forums](https://www.raspberrypi.org/forums/viewtopic.php?t=224629). People speculate that Wolfram no longer licenses Mathematica for Raspbian, which seems strange/doubtful to me given that [11.3 for the RPi was released just 3 months ago](http://community.wolfram.com/groups/-/m/t/1349489), i.e. development seems to be ongoing.
Can anyone from Wolfram comment please?Szabolcs Horvát2018-10-14T14:56:10ZCorrelation of elements in time series
http://community.wolfram.com/groups/-/m/t/1518622
>Let $y_t = 0.8y_{t-1} + \epsilon_t$ where $\mathbb{E}[\epsilon_t] = 0$ and $\mathrm{Var}[\epsilon_t] = 1$. The time series is a strictly stationary sequence and each element is normally distributed. Hence $\mathbb{E}[y_t]$ and $\mathrm{Var}[y_t]$ are both constants. In particular, $\mathbb{E}[y_t]$ = $\mathbb{E}[y_{t-1}]$ and $\mathrm{Var}[y_t]$ = $\mathrm{Var}[y_{t-1}]$. Let $\rho(T)$ be the correlation between $y_t$ and y_{t-1}. Find $\rho(1)$ and $\rho(2)$.
Here is what I did for ρ(1):
ρ(1) = Corr(y<sub>t-1</sub>, y<sub>t</sub>) = Cov(y<sub>t</sub>, y<sub>t-1</sub>) / (σ<sub>y<sub>t</sub></sub> * σ<sub>y<sub>t-1</sub></sub>)
Cov(y<sub>t</sub> , y<sub>t-1</sub>) = Cov(y<sub>t-1</sub>, 0.8y<sub>t- 1</sub>+ε<sub>t</sub>) = 0.8Cov(y<sub>t-1</sub>, y<sub>t-1</sub>) + Cov(y<sub>t-1</sub>, ε<sub>t</sub>)
= 0.8Var(yt-1)+ E((y<sub>t-1</sub> - (0.8y<sub>t-1</sub>))(ε<sub>t</sub> - E(ε<sub>t</sub>))) = 0.8Var(y<sub>t-1</sub>) + E((0.2y<sub>t-1</sub>)(ε<sub>t</sub>))
= 0.8Var(y<sub>t-1</sub>) + 0.2E(y<sub>t-1</sub>)E(ε<sub>t</sub>) = 0.8Var(y<sub>t-1</sub>)
=>√((0.8Var(y<sub>t-1</sub>)))<sup>2</sup> / Var(y<sub>t-1</sub>)<sup>2</sup>)= √0.8 = 0.8944
Did I do this right and if so, wouldn't ρ(2) be the same thing? I was also confused as to how $\mathbb{E}[y_t]$ could be equal to $\mathbb{E}[y_{t-1}]$ when $\mathbb{E}[y_t]$ = 0.8$\mathbb{E}[y_{t-1}]$Nicholas Soteropoulos2018-10-17T20:48:18ZFinding a continuous function that minimizes an integral expression
http://community.wolfram.com/groups/-/m/t/1518788
I am trying to find a continuous function $x(t)$ defined over non-negative real numbers that minimizes the expression below:
>$$\frac{\nu y_1 + (1-\nu)y_2}{y_0}$$
where
- $\displaystyle \nu = \int_{0}^{\infty} (1-x(t)) f'(t) dt$,
- $\displaystyle y_0 = \int_{0}^{\infty} (1-f(t))(1-x(t)) dt$,
- $\displaystyle y_1 = \int_{0}^{\infty} (1 - \frac{x(t)}{C_1 x(t) + 1}) dt$,
- $\displaystyle y_2 = C_2$,
$C_1$ and $C_2$ are positive real constants,
$f(t)$ is a probability density function. $f(t)$ is differentiable everywhere. And I need to find a function $x(t):\mathbb{R^+}\cup \{0\}\to\mathbb{R^+}$.
I tried to see whether the Euler equation from the calculus of variations can help. However I could not find a way to progress.omer subasi2018-10-17T22:36:03ZWhat is the default precision of ` when not specifying a digit after it?
http://community.wolfram.com/groups/-/m/t/1518918
If the symbol ` has no digits after it, what is the precision of the number understood to be?
Here is a the sample code:
DKReplace = {70.6`, 74.2`, 80.1`, 75.3`, 55.6`, 55.5`, 62.6`, 64.9`,
80.1`, 102.5`};
Thank you,
BenoitBenoit Cordoba2018-10-17T23:43:08ZCreate an interface for a drinks vending machine?
http://community.wolfram.com/groups/-/m/t/1518375
Hello everyone, if someone were available, I would need a hand in the making of a mathematical machine, I thought to realize the interface of a distributor of drinks that tells me to enter the money, select the code concerning the drink and then, in based on the money inserted, give me rest if the cost of the drink is lower than what is entered. However, since I should use wolfram mathematica I do not know how to set the algorithm, as I am not very familiar with this program.
See the following code:
stringa1 = "Inserire soldi:";
stringa2 = "Inserire codice bibita:";
Column[{{InputField[stringa1, String],
InputField[Dynamic[beta], Number],
Button["Clicca qui",
Print[InputField[stringa2, String],
InputField[Dynamic[alph], String]]]}}]
If someone would give me a hand I would do a big favor .... thanks in advance.Pasquale Rossi2018-10-17T20:06:52ZGet the Real part of a complex function with ComplexExpand and Re?
http://community.wolfram.com/groups/-/m/t/1511141
So I declare a complex function r[w] and I want to create another function U[w] which is defined by the real part of r[w]. So I try to use the embedded Re[] function but it returns a weird expression.
r[w]=200/(I*w*(10*I*w + 1))
If I do ComplexExpand[r[w]] I get -(2000/(1 + 100 w^2)) - (200 I)/(w (1 + 100 w^2)).
So I know that U[w] should be -(2000/(1 + 100 w^2)).
But the Re[r[w]] function returns 200 Im[1/((1 + 10 I w) w)]. Simplifying this expression by using Simplify[] and FullSimplify[] wouldn't help (even assuming that w is Real).
So how do I get the real and the imaginary part of my complex function r[w]?Daniel Voloshin2018-10-14T09:23:12ZTwelve Prisms
http://community.wolfram.com/groups/-/m/t/1517102
My friend Gianni Sarcone recently built a 12 prism construction.
![twelve prisms][1]
So I had to build one myself. I also built in in Mathematica. To my surprise, I was able to simplify it down to three points.
base={{4,4,7},{3,6,6},{2,5,8}};
prismp=Join[base,-(Reverse/@base)];
prismf={{1,2,3},{4,5,6},{1,2,4,5},{1,3,6,5},{2,3,6,4}};
tetrahedralGroup ={{{-1,0,0},{0,-1,0},{0,0,1}},{{0,-1,0},{0,0,1},{-1,0,0}},{{0,0,1},{-1,0,0},{0,-1,0}},{{0,0,-1},{1,0,0},{0,-1,0}},{{0,1,0},{0,0,-1},{-1,0,0}},{{1,0,0},{0,1,0},{0,0,1}},{{0,-1,0},{0,0,-1},{1,0,0}},{{-1,0,0},{0,1,0},{0,0,-1}},{{0,0,1},{1,0,0},{0,1,0}},{{1,0,0},{0,-1,0},{0,0,-1}},{{0,0,-1},{-1,0,0},{0,1,0}},{{0,1,0},{0,0,1},{1,0,0}}};
Graphics3D[{Opacity[.8],Table[Polygon[prismp[[#]].tetrahedralGroup[[n]]]&/@prismf,{n,1,12}]}, Boxed-> False, SphericalRegion->True,ImageSize-> {800,800},ViewAngle-> Pi/9]
![twelve prisms][2]
Maybe try out ViewAngle -> Pi/600, ViewPoint -> {200, 0, 0}
![12 prisms from far away][3]
Sweet.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=twelveprisms.jpg&userId=21530
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=12prismWL.jpg&userId=21530
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=12prismfar.jpg&userId=21530Ed Pegg2018-10-16T22:24:27ZAlgorithmic Information Dynamics Course
http://community.wolfram.com/groups/-/m/t/1491903
The [Algorithmic Information Dynamics course][1] promoted and distributed by the Santa Fe Institute is coming to an end. Sponsored by Wolfram Research, the course students made heavy use of the **Wolfram Language** to follow lectures, read, write and share code from the cloud. This has been an enriching experience for both instructors and students and people may want to share their thoughts about it.
[![enter image description here][2]][1]
### **About the Course:**
Probability and statistics have long helped scientists make sense of data about the natural world — to find meaningful signals in the noise. But classical statistics prove a little threadbare in today’s landscape of large datasets, which are driving new insights in disciplines ranging from biology to ecology to economics. It's as true in biology, with the advent of genome sequencing, as it is in astronomy, with telescope surveys charting the entire sky.
The data have changed. Maybe it's time our data analysis tools did, too.
During this three-month online course, starting June 11th, instructors Hector Zenil and Narsis Kiani will introduce students to concepts from the exciting new field of Algorithm Information Dynamics to search for solutions to fundamental questions about causality — that is, why a particular set of circumstances lead to a particular outcome.
Algorithmic Information Dynamics (or Algorithmic Dynamics in short) is a new type of discrete calculus based on computer programming to study causation by generating mechanistic models to help find first principles of physical phenomena building up the next generation of machine learning.
The course covers key aspects from graph theory and network science, information theory, dynamical systems and algorithmic complexity. It will venture into ongoing research in fundamental science and its applications to behavioral, evolutionary and molecular biology.
[1]: https://www.complexityexplorer.org/courses/63-algorithmic-information-dynamics-a-computational-approach-to-causality-and-living-systems-from-networks-to-cells
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2018-10-10at4.41.08PM.png&userId=20103Hector Zenil2018-10-03T09:15:56ZSolve a coupled second order differential equations of two variables?
http://community.wolfram.com/groups/-/m/t/1511565
Hello friends!!
I want to solve coupled two second order and one first order differential equations of two variables
and want to plot 3D graph. My code is attached and it is giving errors.
Kindly help me to remove the errors.shivi sv2018-10-14T15:01:18ZOutput error
http://community.wolfram.com/groups/-/m/t/1511197
I am new to Mathematica and still learning the language. I have question involving a mass -spring system and need to solve a second order ODE for multiple points at multiple times but can't write it properly. Please help the question and code written is attached.![enter image description here][1]Areeb Qureshi2018-10-14T14:37:36ZSet up a ColorFunction on the following DensityPlot?
http://community.wolfram.com/groups/-/m/t/1511933
Hi,
I have a function, say f[x,y] that can return only 3 values: +1, 0, and -1 (it is similar to Sign, but comes from stability analysis of a control system with 2 state variables) I would like to use DensityPlot so that +1, 0 and -1 map to red, white and blue, respectively, over a specified (x,y) plot region Question: how do I set ColorFunction to achieve that mapping? The plot statement is simply
DensityPlot [f[x,y],{x,min,max},{y,min,max}, PlotPoints->50, ... ]
where ... are additional options.Carlos Felippa2018-10-15T00:06:38ZRandomness of the number C[10]!, a candidate for replace Pi (random basis)
http://community.wolfram.com/groups/-/m/t/1485074
Hello people of the community, I'm an enthusiast of **Mathematica** and **Wolfram|Alpha** who's been busy for the last few days with a project on possible numerical candidates to be used as random alternative bases for various applications. As I know there are amazing mathematical friends in the community, I decided to humbly expose my work and ask about opinions, etc. Only for the purpose of presenting some of my ideas and also to start an informal discussion on this kind of subject: number randomness. And maybe it can also be useful for someone here.
To begin with, I understand that the randomness that I speak in this text is not truly random, but it serves as the basis for almost-random operations and distributions that need that specific degree of trust.
In order to study the randomness of the transcendental numbers, candidates for transcendental and notable irrational numbers, I used a table base and developed a digit counting workbook. I only used numbers with 10000 decimal digits for the study (generated using **Mathematica** and the data later adapted to data workbook). Below is the example of the interface I used with the Pi number:
![enter image description here][1]
Each workbook of data like this above is a point on a chart, that is, many similar to this will result in the characteristic curve of each number review.
In this study I compared four different specific characteristics (Y-axis). Using the workbook I could detail these quantities as the digits increased to 10000 on the X-axis. I used the transcendental number Pi to start the study. In this study I made my own version of properties to study the numbers and are not necessarily the conventional way of doing it. Given:
C = Deviation of the average arithmetic between all the decimal digits in the range.
S = Deviation of the average count of different digits: how many nine, how many 8 etc...
T = It measures the difference of how many numbers are between 0 and 4 in contrast to those between 5 and 9, such as a coin toss, result between rounding up or down situations.
A = Total number of digits forming or part of doubles, triples, etc.: 11,222,5555, 333333333... (in the interval studied).
I've tested several numbers and their combinations. As for example: **E^Pi, Pi^E, E^sqrt(2), 2^sqrt(2), Zeta (3), Gamma(1/3), Ln(2), Ln(Pi), E^(1/Pi), E+Pi, GoldenRatio, EulerGamma, E+Ln(2)+EulerGamma**, etc... around 30 different numbers, preferably transcendentals, irrational and other notorious candidates. There are two types of accuracy in this project, some I made with with 31 data points and some more detailed with 91 data points.
Below is the detailed graph of **Pi** referring to the characteristics already stipulated:
![enter image description here][2]
In this graph each vertical line is one point to the curve and has a separation of 110 digits, there are 91 points from 100 to 10000 digits on the X-axis.
Below are a few more examples with other notable numbers:
E Number
![enter image description here][3]
Gamma(1/3) Number
![enter image description here][4]
Ln(2) Number
![enter image description here][5]
Each of these charts above have the space between the vertical lines of 330 digits (X-axis) and use 31 points between 100 and 10000. They represent the characteristic curve of each number (Y-axis).
Note 1: Realize that the closer to the X-axis are the curves, in all graphics, the more well distributed and favored is the number for its use in random applications.
Then the following: I calculated the **AREA** below the curve in the graphs to characterize each of its value. The method I used was to calculate the area through average trapezoids formed by the arithmetic mean, so consequently I considered its own degree of precision.
Note 2: The important point in this study **IS NOT** the absolute values that I found (because I used a specific method), **BUT** the comparison of the values between the different numbers, since I used the same process in all objects of study, making it possible to compare. Below is the table for four important numbers using the accuracy of 31 points.
![enter image description here][6]
The Pi number has the lowest frequency to form repetitions of ALL the numbers tested (..would that be the manifestation of it irrationality?).
Well, after a sequence of tests and more tests, in this quest to find candidates equal or almost good as Pi in this characteristic, I found by chance a very good candidate number: the number **C (10)!** , or **ChampernowneNumber(10)!** (! = factorial):
I used **Mathematica** to generate the test numbers (examples):
![enter image description here][7]
In this example above are the first 500 digits of the numbers C(10) and C(10)!, but in the real study I used 10000 digits (also generated by **Mathematica**).
Examples of digit count according to the amount of total digits. The left is the C (10)! And the right is Pi:
![enter image description here][8]
Below is the result of the workbook I generated for the C (10)! using 31 points of precision:
![enter image description here][9]
Full chart of Champernowne (10)! (now with 91 points, 110 in 110 digits, 100 to 10000):
![enter image description here][10]
![enter image description here][11]
Comparing the data I got for Pi e C(10)! numbers (max accuracy, chart of 91 points):
![enter image description here][12]
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Pigraph0.jpg&userId=1316061
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Pigraph1.jpg&userId=1316061
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=e.jpg&userId=1316061
[4]: http://community.wolfram.com//c/portal/getImageAttachment?filename=gamma13.jpg&userId=1316061
[5]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ln2.jpg&userId=1316061
[6]: http://community.wolfram.com//c/portal/getImageAttachment?filename=tablei.jpg&userId=1316061
[7]: http://community.wolfram.com//c/portal/getImageAttachment?filename=champernowneini.jpg&userId=1316061
[8]: http://community.wolfram.com//c/portal/getImageAttachment?filename=tabledual.jpg&userId=1316061
[9]: http://community.wolfram.com//c/portal/getImageAttachment?filename=tablei2.jpg&userId=1316061
[10]: http://community.wolfram.com//c/portal/getImageAttachment?filename=champernowne!.jpg&userId=1316061
[11]: http://community.wolfram.com//c/portal/getImageAttachment?filename=tablef.jpg&userId=1316061
[12]: http://community.wolfram.com//c/portal/getImageAttachment?filename=conclusao.jpg&userId=1316061
I conclude that: of all the numbers tested (transcendental, irrational, etc.) the number that has the characteristic of not-repeating-numeral to those of Pi is the **ChampernowneNumber (10)**! : a possible candidate to replace it in applications that need randomness and it IS NOT possible or convenient to incorporate Pi (is that a best alternative candidate? ). Currently I take 2 minutes to do a fast previous checkup on any number with the workbook, 1 hour to create and analyze completely with the chart 31 points and 3 hours for the chart of 91 points.
Please if you liked the work I did let me know giving a LIKEClaudio Chaib2018-09-29T21:29:53ZPseudo-Dynamic Approach to the Numerical Solution of Nonlinear PDEs
http://community.wolfram.com/groups/-/m/t/1516751
New *THE MATHEMATICA JOURNAL* article:
----------
[Pseudo-Dynamic Approach to the Numerical Solution of Nonlinear Stationary Partial Differential Equations][1]
--------------------------------------------------------------------
*by ALEXEI BOULBITCH*
--------------------------------------------------------------------
ABSTRACT: This article presents a numerical pseudo-dynamic approach to solve a nonlinear stationary partial differential equation (PDE) *S* with bifurcations by passing from *S* to a pseudo-time-dependent PDE *T*. The equation *T* is constructed so that the desired nontrivial solution of *S* represents a fixed point of *T* . The numeric solution of *S* is then obtained as the solution of *T* at a high enough value of the pseudo-time.
- [Read full text »][2]
- [Submit an article »][3]
![enter image description here][4]
[1]: http://www.mathematica-journal.com/2018/10/pseudo-dynamic-approach-to-the-numerical-solution-of-nonlinear-stationary-partial-differential-equations/
[2]: http://www.mathematica-journal.com/2018/10/pseudo-dynamic-approach-to-the-numerical-solution-of-nonlinear-stationary-partial-differential-equations/
[3]: http://www.mathematica-journal.com/submit-article/
[4]: http://www.mathematica-journal.com/data/uploads/2018/10/Boulbitch_Output_1.gifModeration Team2018-10-16T18:22:53ZGet right transformation of a uniform distribution leading to a Pareto one?
http://community.wolfram.com/groups/-/m/t/1515688
Hello,
this is a question about the transformation of a uniform distribution leading to a "standard" Pareto one.
Here are two formulas A and B (densities) resulting from this transformation:
A[v_] := (1/D[1/u^(1/a), u]) /. u -> 1/v^a
D[1/u^(1/a), u] // InputForm // Print
B[v_] := -(u^(-1 - 1/a)/a) /. u -> 1/v^a
B is correct, while A is not (does not integrate to 1 on [1,Infinity[ ). Why?
Regards,
ClaudeClaude Mante2018-10-16T13:23:07ZUse an exponential model to define a function?
http://community.wolfram.com/groups/-/m/t/1515426
Hello,
I have created exponential and logistic models, but I do not know how to define a function for them and solve the following problems. I went to math lab tutors multiple times, and nobody knew how to solve them, even after browsing for various commands in the mathematica library. If anyone could help me solve these, I would really really appreciate it. I have already created the code for the plots.Keanu Davis2018-10-16T05:08:47ZSolve system of 2nd order ODE?
http://community.wolfram.com/groups/-/m/t/1513818
New to Mathematica. Need to plot the position and velocity of 14 points. 2 are fixed 12 are in the form of a system of equations. what mistake am I making?
g = 10;
ic1 = {y[x, 0] == 0}
bc = {y[-1/2, t] == 0, y[1/2, t] == 0}
system = Table[
D[y[x, t], {t,
2}] == -100 (2*(y[x, t]) - y[x - 1/13, t] - y[x + 1/13, t]) -
10 ((2*D[y[x, t], {t, 1}]) - D[y[x - 1/13, t], {t, 1}] -
D[y[x + 1/13, t], {t, 1}]) + g, {x, -1/2 + 1/13, 1/2 - 1/13,
1/13}]
functions = Table[y[x, t], {x, -1/2, 1/2, 1/13}]
DSolve[{system, bc, ic1}, functions, t]Areeb Qureshi2018-10-15T15:29:11ZWhich version of Mathematica is available on Raspberry Pi ?
http://community.wolfram.com/groups/-/m/t/1349489
Hello,
I recently added Mathematica on my Raspberry 3 (originally with Raspbian Lite), and got the 11.0.1.
Any attempt to get the 11.2 version by a classical upgrade process
sudo apt-get dist-upgrade wolfram-engine
just answers that I am up-to-date... However I can read in the group lot of posts concerning 11.2 !
How can I get it ? I wouldn't like to reinstall Raspbian, as it is a special image.
Thank you for your help,
Yvesyves papegay2018-05-31T13:46:34ZMake a function that can find the 3 rod of a number?
http://community.wolfram.com/groups/-/m/t/1511774
Here you can see my code, as it is for now. Must admit, I'm kinda lost why it doesn't work. I think there is something about the syntax I'm not understanding.
Best regards,
kobikrod2[x0_] := Module[{xny, xgl},
xs = If[Positive[x0], xs = N[x0], Print["Tallet er ikke positivt"]]
xgl = xs // 2 ;
xny++ 1 = 1/3 (2*xgl + (xs/xgl^2));
While[xny != xgl, xgl = xny;
xny = xgl + 1 = 1/3 (2*xgl + (xs/xgl^2))];
xny]Martin Friis2018-10-14T20:11:48ZInterface with Arduino mega in Mathematica?
http://community.wolfram.com/groups/-/m/t/1514918
I am currently attempting to interface with Arduino mega but the basic Arduino functions don't work as they are not specifically for the mega. Any way I can use a serial device open or something else to access this Arduino mega? The Arduino would be used to control stepper motors and other little things. Any tips would be of great help.Adriel Rios Nieves2018-10-15T20:12:18ZLinguistics Curator
http://community.wolfram.com/groups/-/m/t/1514714
Wolfram|Alpha is seeking a Linguistics Curator to join our Wolfram|Alpha Content Development team. We are looking for a creative individual with strong critical thinking, problem solving, and language skills. As a Linguistics Curator, you will be able to work in a flexible, productive, and fast-paced environment, contributing to the development and support of Wolfram|Alpha’s natural language understanding capabilities across a wide range of knowledge domains.
**Skills Required:**
- Fluency in written English (additional languages are a plus)
- Familiarity with and/or ability to assimilate technical jargon in
diverse specialized knowledge areas
- Basic programming experience (Wolfram Language preferred)
- Experience with content versioning systems (CVS, Git) is highly
desirable
**Location:** Champaign, Illinois
Wolfram is an equal opportunity employer and values diversity at its company. Women, people of color, members of the LGBTQ community, individuals with disabilities and veterans are strongly encouraged to apply.
Click [here][1] to apply!
[1]: http://www.wolfram.com/company/careers/opportunities/#op-93432-linguistics-curatorHolly Glenn2018-10-15T18:55:51ZSoftware Developer—Business Systems R&D
http://community.wolfram.com/groups/-/m/t/1514190
Wolfram, creator of Mathematica, Wolfram|Alpha and the Wolfram Language, has an exciting opportunity available for a Software Developer to join its Business Systems R&D team and assist with the ERP project. The ERP project is working on creating a new business system that will use the Wolfram technology stack on the company’s own Wolfram Enterprise Private Cloud. The candidate will need to be energetic about new, daily challenges, as this project is being built from the ground up. The candidate will also need to be open to working in a very collaborative environment. The job will involve working with all groups that use the company’s business data, including finance, sales, customer support, purchasing and more.
**Responsibilities:**
- Developing front end applications in the Wolfram Cloud
- Developing back end applications using the Wolfram Language
- Unit testing development efforts
- Performing peer code reviews
**Minimum qualifications:**
- Wolfram Language experience (2+ years)
- API development experience (2+ years)
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specifically GIT Familiarity with databases, specifically Postgres
Business and/or system analysis experience
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[1]: http://www.wolfram.com/company/careers/opportunities/#op-214254-software-developerbusiness-systems-rdHolly Glenn2018-10-15T18:52:54ZOuter Billiards. How to create a test to skip triangle corner in for loop?
http://community.wolfram.com/groups/-/m/t/1487490
Hey Everyone! I'm currently working on a problem in a course on mathematical modeling concerning Outer Billiards. I'm supposed to write a program that does the following:
> Start with a ball (a point particle) somewhere outside an equilateral triangle with side length equal to 1. You have two possibilities here and you select one of them. When it arrives at the corner it has traveled a distance d1. Then the particle continues in the same direction as before the same distance d1 There it changes direction momentarily and moves towards the other corner. Then the procedure is repeated, at the second corner it has traveled a distance d2 and it continues in the same direction the same distance d2, etc.
One problem that I've encountered is that for some points the trajectory of the point particle crosses the interior of the triangle, which is not allowed. Therefore I would like to create a test inside of my for loop which says that: "IF the trajectory towards a corner crosses the interior of the triangle, move instead to the next corner." Now, my lecturer gave me a hint that one can use determinants in order to make a pretty easy test, but I find it somewhat hard to understand intuitively. So I would like to make another test, but I don't know how exactly. Here is the program that I'm working on:
corner = {{1/2, Sqrt[3] /2}, {0, 0}, {1, 0}};
ourtriangle = Triangle[{corner[[1]], corner[[2]], corner[[3]]}];
p0 = {2, 2};
plotpoints = {p0};
cornerindex = 1;
n = 3;
For[i = 1, i < n, i++,
p1 = 2*corner[[cornerindex]] - p0;
p0 = p1;
AppendTo[plotpoints, p1];
cornerindex = Mod[i, 3] + 1;
]
traj = Table[plotpoints[[i]], {i, n}];
plot1 = Graphics[{Dashed, Line[traj]}];
Show[plot1, Graphics[ourtriangle], Axes -> False]
This yields the following graph:
![enter image description here][1]
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Project_1_FINAL.jpg&userId=1487470
So, in this case I would like the trajectory to instead move towards the right-most corner but I really dont know how. Could someone please give me at least a hint?
Thank you all.Victor Galeano2018-10-01T14:08:05ZHow can I completely simplify the result of "PiecewiseExpand" ?
http://community.wolfram.com/groups/-/m/t/1509500
![figure 1][1]
Hi, guys. How can I completely simplify the result of "PiecewiseExpand" in the picture? Because the first line of the result obviously does not exist. What I want to derive is that it disappears automatically if this result does not exist. In addition, do we have any code to realize the exact conditions of "true" ? Thank you very much!
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=123456.jpg&userId=178384EditProfile FillName2018-10-13T09:46:17ZSolve iteration for a cube root, by using For, While or Do?
http://community.wolfram.com/groups/-/m/t/1512199
You have a cube Root iteration:
Xi1 = 1/3*(2*Xi0 + n/(Xi0^2)), where i = 1,2,3,4,5
I want to use For, While or Do command...
How do I solve this?Zain Ahmed2018-10-15T04:55:11ZVisualize a root of one variable equation with Manipulate?
http://community.wolfram.com/groups/-/m/t/1497914
Hello. I am trying to visualize root of third degree one variable equation. Delta^3-C0*delta+2==0, C is between [0,10]. But there occurs an error. Could you help to fix this problem. Thanks a lot. Here is the code:
Manipulate[
f1 = \[CapitalDelta]0^3 - С*\[CapitalDelta]0 + 2;
sol1 = FindRoot[f1 == 0, {\[CapitalDelta]0, 0.9}];
Plot[ f1, {\[CapitalDelta]0, 0, 1}, PlotRange -> 0.1,
Epilog -> {{PointSize[0.03], Point[{\[CapitalDelta]0 /. sol1, 0}]},
Text["\!\(\*SubscriptBox[\(\[CapitalDelta]\), \(0\)]\)=", {0.75, \
-0.05}], Text[
ToString[N[\[CapitalDelta]0 /. sol1, 10]], {0.9, -0.05}]}]
, {C0, 0.1, 5}]Torebek Zhumabek2018-10-07T10:05:53ZIs there documentation on File/New/Package?
http://community.wolfram.com/groups/-/m/t/1511712
In the File menu there is an opportunity to open a file as a package using File/New/Package. That opens a specialized GUI with the option to run and debug code. When we look up documentation on this here is what we get:
![help entry][1]
Does anyone know the whereabouts of some useful documentation, or even a tutorial giving the intended use of this capability and an example?
Kind regards,
David
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=1317Capture.PNG&userId=98179David Keith2018-10-14T16:13:12ZSpeed up evaluation of this integral?
http://community.wolfram.com/groups/-/m/t/1508724
I am trying to evaluate the integral
$$ \int_0^{2\pi}\frac{D_{11}^2+2D_{12}^2+D_{22}^2+D_{33}^2}{1+e\cos x(t)}dx $$
Where $D_{ij}$ are third derivatives wrt $t$ as defined below.
a[psi_] := k1/(1 + e*Cos[psi]);
d[psi_] := p1/(1 + e*Cos[psi]);
D11 = D[a[x[t]]*(Cos[x[t]]^2 - 1/3), {t, 3}];
D12 = D[a[x[t]]*Cos[x[t]]*Sin[x[t]], {t, 3}];
D22 = D[a[x[t]]*(Sin[x[t]]^2 - 1/3), {t, 3}];
D33 = D[-a[x[t]]/3];
To do this I have written the input
Assuming[Element[k1, Reals] && Element[e, Reals] &&
x'[t] == p2/(d[x[t]]^2) && Element[p2, Reals] &&
Element[p2, Reals],
Integrate[(D11^2 + 2*D12^2 + D22^2 + D33^2)/(1 + e*Cos[x[t]])^2, {x[
t], 0, 2*Pi}]]
This is taking a very long time to evaluate (has been running for hours), is it OK to specify to *Mathematica* that I have the condition $\dot{x}=\frac{p_2}{d(x(t))^2}$ in this manner? How could this be sped up?
This integral arose in the study of the loss of energy of an orbiting mass due to gravitational radiation.tom ri2018-10-12T18:24:18ZSubdividePoints
http://community.wolfram.com/groups/-/m/t/1511449
MIT's [MPB](https://mpb.readthedocs.io/en/latest/) and [MEEP](https://meep.readthedocs.io/en/latest/) programs have a very interesting function called **interpolate** (and a variant **kinterpolate-uniform**), which basically creates points between a set of points, working like the Mathematica's `Subdivide` function.
Unfortunately `Subdivide` does not work with more than two vectors, subdividing only the endpoints. We can easily extend this behavior with the new functions:
SubdividePoints[pts_List?MatrixQ, n_Integer] := Block[{pt},
pt = Flatten[Table[
pts[[i]]*(1-t) + pts[[i+1]]*t
, {i, Length@pts-1}, {t, Subdivide[0,1,n+1]}]
, 1];
pt = Delete[pt, Position[Norm /@ Differences@pt, 0]]
]
And the another one for a uniform coverage.
SubdividePointsUniform[pts_List?MatrixQ, n_Integer] := Module[{L, m, pt},
L = (Norm /@ Differences@pts);
m = Round[L/Min[L/n]];
pt = Flatten[Table[
pts[[i]]*(1-t) + pts[[i+1]]*t
, {i, Length@pts-1}, {t, Subdivide[0,1,m[[i]]+1]}]
, 1];
pt = Delete[pt, Position[Norm /@ Differences@pt, 0]]
]
A simple example of usage would be creating points in the Brillouin zone of a square:
pts = {{0,0}, {1,0}, {1,1}, {0,0}}/2;
SubdividePoints[pts, 3] // ListPlot
SubdividePointsUniform[pts, 3] // ListPlot
![img][1]
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=2018-10-14_134741.png&userId=845022Thales Fernandes2018-10-14T16:49:39ZAvoid weird formatting of the following mathematical expressions?
http://community.wolfram.com/groups/-/m/t/1511150
For some reason Mathematica keeps returning dots in between variables and their coefficients. So instead of "1000s" I get "1000.s". And even more weird, instead of "2500" I get "2500.".
Why is it happening and how do I get rid of it?Daniel Voloshin2018-10-14T09:33:32ZSimulate the motion of the Earth around the Sun based on Kepler's Law?
http://community.wolfram.com/groups/-/m/t/1500089
I am using Mathematica 10.3. I want fo perform a computational analysis of the motion of the Earth around the sun based on Kepler’s laws.
Here is my code so far.
eulerStep[{t_, state_List}, h_, f_List] := {t + h,
state + h Through[f[{t, state}]]}
solveSystemEuler [{t0_state0 _}, h_, n_Integer, f_List] :=
NestList[eulerStep[#, h, f] &, {t0, state0}, n]
midptStep[{t_, state_List}, h_, f_List] := {t + h,
state + h Through[
f[{t + 1/2 h, state + 1/2 h Through[f[{t, state}]]}]]}
solveSytemMidPt[{t0_, state0_}, h_, n_Integer, f_List] :=
NestList[midptStep[#, h, f] &, {t0, state0}, n]
L = 1/2 m (x'[t]^2 + y'[t]^2) + GMm/Sqrt[x[t]^2 + y[t]^2];
D[D[L, x'[t]], t] - D[L, x[t]] == 0
D[D[L, y'[t]], t] - D[L, y[t]] == 0
xdot[{t_, {x_, vx_, y_, vy_}}] := vx
vxdot[{t_, {x_, vx_, y_, vy_}}] := -x/(x^2 + y^2)^(3/2)
ydot[{t_, {x_, vx_, y_, vy_}}] := vy
vydot[{t_, {x_, vx_, y_, vy_}}] := -y/(x^2 + y^2)^(3/2)
start = {1, 0, 0, 1};
fcns = {xdot, vxdot, ydot, vydot};
orbit = solveSystemEuler[{0, start}, 0.01, 800, fcns];
<< Statistics`DataManipulation`
xypts = Column[Column[orbit, 2], {1, 3}];
ListPlot[xypts, PlotJoined -> True];
Running the program gave the following error messages.
![enter image description here][1]
Please help me to fix my code.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Capture.JPG&userId=1499975Senlau Minto2018-10-08T03:45:10ZIs Mathematica 11 compatible with Mac OS Mojave
http://community.wolfram.com/groups/-/m/t/1479746
any problem with Mojave before I switch to it?michel2018-09-26T02:01:06ZPlot the following differential equation over a larger time window?
http://community.wolfram.com/groups/-/m/t/1510304
I am using differential equations to determine the rate of formation of certain compounds in an enzymatic reaction. I am having an issue however, when graphing the rate of formation of one of the compounds over 1,800 seconds (tmax) where I get a very strange graph that has many "jumps". However, this issue is resolved when I reduce the window of time to 30 seconds (tmax2). I believe that the program is having issues graphing the differential equation over the larger window of time. Is there any way I can resolve this or a better alternative to this?
Thank you very much,
NikNik Teodo2018-10-13T19:04:35ZUse external APIs and data wrangling?
http://community.wolfram.com/groups/-/m/t/1404817
Hi, I am considering using the Wolfram Cloud to host a project that makes use of API calls to a third party (never done production deployments in the WC before). The problem is that API calls (in the default way provided by the third party) contain metadata and even the key-value pairs included in the response need to be cleaned up (the only thing that is relevant to me is the last value, in the example below that would be the number 1.9082*^7). Is there any way to make the call so that just that value is extracted (or at least the list put in usable key-value dataset format?)? If not, what would be the most efficient way to clean up the output, to simply assign that value to a variable? The code will be making many simultaneous API calls, and I'll really prefer to avoid performance issues -not to waste too much computing power wrangling data. Thanks!
{meta->{request->{granularity->Daily,start_date->2018-01-27,end_date->2018-01-31,limit->Null },status->Success,last_updated->2018-07-31},value->{{date->2018-01-27,value->1.48229*^7},{date->2018-01-28,value->1.42697*^7},{date->2018-01-29,value->1.67565*^7},{date->2018-01-30,value->1.91857*^7},{**date->2018-01-31,value->1.9082*^7**}}}George W2018-08-14T05:33:17ZAdd data anonymously, no metadata, geolocation, etc. with DatabinAdd?
http://community.wolfram.com/groups/-/m/t/1509842
Is there a way to either add data to a databin anonymously, meaning with no metadata, or to delete metadata from the databin?Philip Maymin2018-10-13T13:02:02ZWhat's the difference between *.m and *.wl file format?
http://community.wolfram.com/groups/-/m/t/1507777
Hello, as a slow beginner this week i am learning about contexts and writing a basic package. Unfortunately I cannot find any explanation about what all the differences between these 2 file formats are. **Saving** a notebook (including a few initialization cells) **as** either format seems to produce the identical file?
In Maeder's book, **knowledge about contexts and creating packages** comes in the *first* chapter. To him, it is essential knowledge, everything else builds upon. In Wellin's book it comes *last*, last chapter. This makes me wonder *how common* it is for the majority of Mma users to write and save their own packages *at all*, as opposed to just using Mma "directly", i.e. working only with **.nb** files, without making any/much use of switching contexts, writing own packages, loading own **.m .wl** package files, and all that spiel.Raspi Rascal2018-10-12T09:46:03ZOutput the numerical expression of a function?
http://community.wolfram.com/groups/-/m/t/1508874
I am a Mathematica beginner working on a problem in the area of quantum mechanics. I adapted [this][1] source code (also attached below) to work with the problem I'm trying to solve. At present, the graphics produced by the code tell me most of what I need to know, but I would like to know how to get Mathematica to output the numerical expression for the wavefunction \[Psi][x].
If someone can take a look at the source code I attached (my own code is quite similar save for a few numerical modifications) and illuminate how to get a numerical expression for Psi, I'd be quite grateful.
I am sure there is a simple solution to this that my lack of Mathematica knowledge is preventing me from seeing. My apologies if this seems like a stupid question, but any help would be greatly appreciated.
Edit: I also posted this question to the Mathematica Stack Exchange forums, and I did not properly link the cross post, which can be found [here][2].
[1]: https://demonstrations.wolfram.com/QuantumWellExplorer/
[2]: https://mathematica.stackexchange.com/questions/183731/how-can-i-get-a-numerical-value-from-a-functionSebastian Perez2018-10-12T23:57:15ZIs FindMaximumFlow function broken?
http://community.wolfram.com/groups/-/m/t/1506931
I ran the example on FindMaximumFlow in the documentation and got the following results.
![enter image description here][1]
My guess is that the answer is wrong. Instead of pairing with Billy, Mary can easily connect to Dustin and Alecia can then pair with Billy. When I run the results in Table to get maximum flows value I get 3 or 4. Am I wrong or is there something strange with the FindMaximumFlow function?
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=problemwithFindMaximumFlow.png&userId=942204Ali Hashmi2018-10-11T19:52:13ZWrite and run C++ code in Mathematica ?
http://community.wolfram.com/groups/-/m/t/1506879
Hi there friends,
I'd like to write and run some C++ programs (as part of a presentation) from within Mathematica. I've seen a simple example in the documentation - using CreateExecutable - but I didn't succeed. Is it something, maybe settings, that I have to do first?
I am using an almost 5 years old MacBook Pro with Mac OS High Sierra and I write C++ programs using X Code 10.0.
Here's what I've got when I tried the example in the documentation :
In[23]:= Needs["CCompilerDriver`"]
In[24]:= hello = CreateExecutable["
#include <stdio.h>
int main(){
printf(\"hello world\\n\");
}
", "hello"]
During evaluation of In[24]:= CreateExecutable::cmperr: Compile error: xcrun: error: active developer path ("/Applications/Xcode 2.app/Contents/Developer") does not exist >>
Out[24]= $Failed
In[25]:= Import["!" <> QuoteFile[hello], "Text"]
During evaluation of In[25]:= StringJoin::string: String expected at position 2 in !<>QuoteFile($Failed). >>
During evaluation of In[25]:= Import::chtype: First argument !<>QuoteFile($Failed) is not a valid file, directory, or URL specification. >>
Out[25]= $Failed
Thank you,
:)Daniel-Claudian Voinescu2018-10-11T20:33:34ZIntegrate a Bessel Function K0(a*x) without the constant 'a' ?
http://community.wolfram.com/groups/-/m/t/1505357
Thanks for reading !
I am having a problem with the numerical integration of the Bessel function
y = BesselK0(a*x)
Since my constant is too large (a = 6800) I am getting the large arguments aproximation for the Bessel K0 function, making the integration difficult.
My question is: Is there some mathematical method or manipulation to remove the constant 'a' from the integration like
y = BesselK0(x)
to make me integrate it like small arguments and then insert the constant 'a' in it somehow after ?
Thank you very much !Romildo Junior2018-10-11T05:37:19ZSimplify a product with f(x,n)?
http://community.wolfram.com/groups/-/m/t/1502463
Hello, I've a problem. Imagine you have a function `f(x,n)` like `f(x,n)=x^n` or `sin(x*n)`. Then you have the product sign. The new formular is then `a(x) = Product[f[x, n], {n, 0, x}]`. And I don't know how I can simplify that equation, or put that product sign away. Do you know how I can simplify an equation like that in general, or in specific `Product[Cos[x/n], {n, 2, -1 + x}]`.Felix H.2018-10-09T14:12:31ZUse solve command to determine a shift value for graph?
http://community.wolfram.com/groups/-/m/t/1507412
Hello,
I have created a code for my graph: Manipulate[Plot[E^-2 x Cos[Pi x] + c, {x, -3, 4}], {c, 0, 3}]
Using the sliders, it appears that F[x] must be shifted up approximately 2.12341 units up in order to pass through the point (1,2).
However, I would like to know how to use the solve command to determine what the exact shift value is for the graph to pass through (1,2).
I have already tried looking up the Mathematica solve command, but I could only find articles for other equations and none that could help me in this case.
Thank you.Keanu Davis2018-10-11T21:07:10ZBugs persisting from 10.0 to 11.3 (just when is it going to get fixed)??
http://community.wolfram.com/groups/-/m/t/1506979
I am actually quite furious as I am writing this post. As an avid user of Mathematica I have personally paid more than 500 dollars since the release of version 9. Today I was trying to implement a code which required the use of `FindMaximumFlow` functionality. I found a bug. The examples that are made by the developer of the language do not work !! Oddly enough, the examples are there to show how a function performs.
FYI: (here is the bug I report) http://community.wolfram.com/groups/-/m/t/1506931
Upon researching a bit I found that another user posted on StackExchange a similar question 2 years and 4 months earlier.
https://mathematica.stackexchange.com/questions/118130/findmaximumflow-generates-a-weird-result
The problem has not been fixed from 10.0 to 11.3 (these include seven releases). My question, when is it going to get fixed? It has clearly not been fixed in the minor releases. If not, then why are we paying so much money for? I am sorry that I have to write like this but something is certainly not right.
This is just one example of a bug. There are others that are still open on StackExchange. Why do they still persist. Please as a user my request is not to introduce more functionality in 12.0 unless you clean/solve all the pending bugs.
Here are a list of questions with the "bug" tag (some of which may not have been addressed):
https://mathematica.stackexchange.com/questions/tagged/bugs
https://mathematica.stackexchange.com/questions/tagged/bugs+graphs-and-networks (for bugs with Graph related functions)
BTW, can anyone from the Graph development team take a note and respond to what I have mentioned?
Thanks !!Ali Hashmi2018-10-11T20:51:42ZEasy generation, testing, and export of audio loops
http://community.wolfram.com/groups/-/m/t/1506499
I wanted to build some samples where the individual notes in a chord would repeat at various rates, and I needed to do it quickly (I had a performance coming up and of course I procrastinated). The traditional method—getting the sounds into a DAW, setting up the individual tracks for each note, setting the fade-ins and fade-outs, testing the loops, exporting, and all the rest—would have been too time consuming. The Wolfram Language made the process a breeze. Plus, I could make adjustments and test them much quicker.
This is the chord:
![a nice, big sounding chord][1]
First, I made a list of keys for when I use `Map[]` to build "the chord" and export the files:
keys = {"1", "2", "3", "4", "5", "6"};
Next, I set up the fade-in time and the durations of my loops. The tempo will be 80 beats per minute, so I needed to convert the number of beats into seconds for `SoundNote[]`:
fadein = N[2/80] *60; (*2 beats*)
time1 = N[24/80] *60; (*6 measures*)
time2 = N[20/80] *60; (*5 measures*)
time3 = N[18/80] *60; (*4.5 measures*)
time4 = N[28/80] *60; (*7 measures*)
time5 = N[16/80] *60; (*4 measures*)
time6 = N[22/80] *60; (*5.5 measures*)
Then, I set up the individual notes to be looped. The fade-in time was defined above, and I wanted the fade-out time to be half the length of the `SoundNote[]`. There was also no need for the final files to be in stereo, so I used `AudioChannelMix[]`:
note1 = AudioChannelMix[AudioFade[Sound[SoundNote["D4", time1, "BlownBottle"]], {fadein, N[time1/2]}, Method -> "Exp"], "Mono"];
note2 = AudioChannelMix[AudioFade[Sound[SoundNote["A4", time2, "BlownBottle"]], {fadein, N[time2/2]}, Method -> "Exp"], "Mono"];
note3 = AudioChannelMix[AudioFade[Sound[SoundNote["E5", time3, "BlownBottle"]], {fadein, N[time3/2]}, Method -> "Exp"], "Mono"];
note4 = AudioChannelMix[AudioFade[Sound[SoundNote["G5", time4, "BlownBottle"]], {fadein, N[time4/2]}, Method -> "Exp"], "Mono"];
note5 = AudioChannelMix[AudioFade[Sound[SoundNote["B5", time5, "BlownBottle"]], {fadein, N[time5/2]}, Method -> "Exp"], "Mono"];
note6 = AudioChannelMix[AudioFade[Sound[SoundNote["E6", time6, "BlownBottle"]], {fadein, N[time6/2]}, Method -> "Exp"], "Mono"];
Time to play! This one will start as a giant chord and then the individual notes will fade in and out:
Map[AudioPlay[ToExpression[StringJoin["note", #]], AudioLooping -> True] &, keys]
Or evaluate one at a time, in any order, and any pause between notes.
AudioPlay[note1, AudioLooping -> True]
AudioPlay[note2, AudioLooping -> True]
AudioPlay[note3, AudioLooping -> True]
AudioPlay[note4, AudioLooping -> True]
AudioPlay[note5, AudioLooping -> True]
AudioPlay[note6, AudioLooping -> True]
After enough testing or listening enjoyment, stop all sounds:
AudioStop[]
After trying out both, I decided to go with the "big chord" approach. It was nice to be able to test both before exporting. It was also nice to be able to quickly adjust the times of the individual notes by going up to my initial definitions.
And now, to export:
Map[Export[StringJoin["loop", #, ".wav"], ToExpression[StringJoin["note", #]]] &, keys]
This gave me a set of similarly named wav files (loop1.wav, loop2.wav, etc), so I could find them easily in my sample pad.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=the-chord.png&userId=1310240Richard Miske2018-10-11T16:52:37ZAnalysis tool in Automatic and Control
http://community.wolfram.com/groups/-/m/t/1506372
Here you have a dynamic interface in which you can visualize the temporal response, root locus plot and Bode diagram of your realimented system introducing the transfer functions. You can easily change the parameters of your system to see how the output changes in real time.
![The program][1]
There is also a guide that will hep you get familiar with the controls quickly.
**NOTE:** The program and the guide are in Spanish because I developed the project in this language as it is my mother tongue.
**Spanish Version:**
Aquí tienes una interfaz dinámica en la que puedes visualizar la respuesta temporal, el lugar de las raíces y el diagrama de Bode de tu sistema realimentado introduciendo sus funciones de transferencia. Puedes cambiar de una forma sencilla los parámetros de tu sistema para ver cómo varían las salidas en tiempo real.
También tienes una guía que te ayudará a familiarizarte rápidamente con los controles.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=30371.2-Programa.png&userId=1078725Carlos Lapuente2018-10-11T15:40:56ZCompleting XKCD curve-fitting post with QRMon
http://community.wolfram.com/groups/-/m/t/1503108
# Introduction
In this notebook/document we apply the monad `QRMon`, \[4\], over data of the XKCD post \[1\]. In order to get the data we used extraction procedure described in \[2\].
*(And, yes, I am probably posting about Quantile Regression and `QRMon` too much...)*
# Extract data
I extracted the data from the image using code in the blog post ["How to Count Cells, Annihilate Sailboats, and Warp the Mona Lisa"](http://blog.wolfram.com/2012/01/04/how-to-count-cells-annihilate-sailboats-and-warp-the-mona-lisa/), \[2\].
img = Import["https://imgs.xkcd.com/comics/curve_fitting.png"]
[Original XKCD image][1].
![enter image description here][2]
Here is the extracted data:
extractedData = {{124.5, 131.3}, {133.9, 112.9}, {150.9, 112.1},
{147.9, 103.9}, {146.5, 97.}, {139.5, 94.5}, {153.5, 94.},
{43.5, 93.}, {144.5, 84.7}, {124.5, 78.}, {72., 74.},
{116.5, 73.7}, {126.5, 71.5}, {125., 62.5}, {145.1, 62.1},
{37.5, 61.}, {69.5, 53.5}, {109.5, 53.7}, {49.9, 45.1},
{77.5, 43.}, {52.5909, 38.8636}, {82.5, 38.5}, {39.5, 33.7},
{78.5, 33.3}, {81.9375, 31.125}, {47.5, 28.}, {104.409, 27.1364},
{24.9, 24.9}, {92.5, 25.}, {142.5, 12.5}};
ListPlot[extractedData, AspectRatio -> 0.9, PlotRange -> All, PlotTheme -> "Detailed"]
![XKCDCurveFittingextractedpoints](https://i.imgur.com/5tbSbI4.png)
# Apply QRMon
Load packages. (For more details see \[4,5\].)
Import["https://raw.githubusercontent.com/antononcube/MathematicaForPrediction/master/MonadicProgramming/MonadicQuantileRegression.m"]
Import["https://raw.githubusercontent.com/antononcube/MathematicaForPrediction/master/MonadicProgramming/MonadicTracing.m"]
Apply the [QRMon](https://github.com/antononcube/MathematicaForPrediction/blob/master/MonadicProgramming/MonadicQuantileRegression.m) workflow within the [TraceMonad](https://github.com/antononcube/MathematicaForPrediction/blob/master/MonadicProgramming/MonadicTracing.m):
trObj =
TraceMonadUnit[QRMonUnit[extractedData]]⟹"lift data to the monad"⟹
QRMonEchoDataSummary⟹"echo data summary"⟹
QRMonEcho[Show[img, ImageSize -> 200], "XKCD:"]⟹"plot one of the curve-fitting XKCD plots"⟹
QRMonQuantileRegressionFit[2, Range[1/10, 9/10, 2/10]]⟹"do Quantile Regression with\n\B-spline basis with 2 knots"⟹
QRMonPlot["Echo" -> False, PlotStyle -> {Black, PointSize[0.025]}, AspectRatio -> 0.9, PlotLabel -> Style["QUANTILE REGRESSION", FontSize -> 24]
⟹"make the plot of the data and\n\regression curves without echoing it"⟹
QRMonEchoFunctionValue["New plot:", xkcdConvert[#] &]⟹
QRMonEcho["Tabulate steps and explanations:"]⟹"echo an explanation message"⟹
TraceMonadEchoGrid;
![XKCDCurveFittingQRMonpipelineecho](https://i.imgur.com/okWTwr2.png)
## Post processing
Here we just make the new XKCD plot made in `QRMon` pipeline above to look more like one of the curve-fitting plots in the original XKCD grid.
Get the plot from the monad and modify it:
newXKCDPlot = (trObj⟹TraceMonadTakeValue⟹QRMonTakeContext)["newXKCDPlot"];
newXKCDPlot = ReplaceAll[newXKCDPlot, HoldPattern[Frame -> _] -> (Frame -> None)];
newXKCDPlot = ReplaceAll[newXKCDPlot, HoldPattern[FrameTicks -> _] -> (Ticks -> None)];
newXKCDPlot = ReplaceAll[newXKCDPlot, HoldPattern[Axes -> _] -> (Axes -> False)];
newXKCDPlot = Show[{Graphics[{GrayLevel[0.8], Line[{{15, 5}, {160, 5}}], Line[{{15, 5}, {15, 140}}]},Epilog -> Text[Style["QUANTILE REGRESSION", Gray, 18], Scaled[{.35, .9}]]], newXKCDPlot}]
Convert the plot into XKCD style:
newXKCDPlot = xkcdConvert[newXKCDPlot];
Make an image with a comment in XKCD style:
xkcdComment =
ImageCrop[
Image[Graphics[
Text[Style["\"ALL KINDS OF WANNABES WITH\nTHEIR INFERIOR METHODS...\"", Black, 20]]]]];
xkcdComment = xkcdConvert[xkcdComment];
Stack XKCD style images:
Grid[{{newXKCDPlot}, {Magnify[xkcdComment, 1.8]}}, Alignment -> Center]
![XKCDCurveFittingwithQuantileRegression](https://I.imgur.com/PKeChQg.png)
# XKCD style (by Simon Woods)
In order to make the notebook self-contained code-wise in this section is provided the code for converting any graphics object into an XKCD style version of it. (See \[3\].)
xkcdStyle = {FontFamily -> "Comic Sans MS", 16};
xkcdLabel[{str_, {x1_, y1_}, {xo_, yo_}}] :=
Module[{x2, y2}, x2 = x1 + xo; y2 = y1 + yo;
{Inset[
Style[str, xkcdStyle], {x2, y2}, {1.2 Sign[x1 - x2],
Sign[y1 - y2] Boole[x1 == x2]}], Thick,
BezierCurve[{{0.9 x1 + 0.1 x2, 0.9 y1 + 0.1 y2}, {x1, y2}, {x2, y2}}]}];
xkcdRules = {
EdgeForm[ef : Except[None]] :> EdgeForm[Flatten@{ef, Thick, Black}],
Style[x_, st_] :> Style[x, xkcdStyle], Pane[s_String] :>
Pane[Style[s, xkcdStyle]], {h_Hue, l_Line} :> {Thickness[0.02], White, l, Thick, h, l},
Grid[{{g_Graphics, s_String}}] :> Grid[{{g, Style[s, xkcdStyle]}}],
Rule[PlotLabel, lab_] :> Rule[PlotLabel, Style[lab, xkcdStyle]]};
xkcdShow[p_] := Show[p, AxesStyle -> Thick, LabelStyle -> xkcdStyle] /. xkcdRules
xkcdShow[Labeled[p_, rest__]] := Labeled[Show[p, AxesStyle -> Thick, LabelStyle -> xkcdStyle], rest] /. xkcdRules
xkcdDistort[p_] :=
Module[{r, ix, iy},
r = ImagePad[Rasterize@p, 10, Padding -> White];
{ix, iy} =
Table[RandomImage[{-1, 1}, ImageDimensions@r]~ImageConvolve~GaussianMatrix[10], {2}];
ImagePad[
ImageTransformation[r, # + 15 {ImageValue[ix, #], ImageValue[iy, #]} &, DataRange -> Full], -5]];
xkcdConvert[x_] := xkcdDistort[xkcdShow[x]]
# References
\[1\] Randall Munroe, ["Curve-Fitting"](https://xkcd.com/2048/), [xkcd.org](https://xkcd.com/). [https://xkcd.com/2048/](https://xkcd.com/2048/) .
\[2\] Shadi Asnai, ["How to Count Cells, Annihilate Sailboats, and Warp the Mona Lisa"](http://blog.wolfram.com/2012/01/04/how-to-count-cells-annihilate-sailboats-and-warp-the-mona-lisa/), (2012), [blog.wolfram.com](http://blog.wolfram.com).
\[3\] Simon Woods, [Mathematica Stackexchange answer](https://mathematica.stackexchange.com/a/11355/34008) to ["xkcd-style Plots"](https://mathematica.stackexchange.com/questions/11350/xkcd-style-plots).
[https://mathematica.stackexchange.com/questions/11350/xkcd-style-plots](https://mathematica.stackexchange.com/questions/11350/xkcd-style-plots).
\[4\] Anton Antonov, ["A monad for Quantile Regression workflows"](https://mathematicaforprediction.wordpress.com/2018/08/01/a-monad-for-quantile-regression-workflows/), (2018), [MathematicaForPrediction at WordPress](https://mathematicaforprediction.wordpress.com/).
\[5\] Anton Antonov, ["Monad code generation and extension"](https://github.com/antononcube/MathematicaForPrediction/blob/master/MarkdownDocuments/Monad-code-generation-and-extension.md), (2017), [MathematicaForPrediction at GitHub](https://github.com/antononcube/MathematicaForPrediction)*, *[https://github.com/antononcube/MathematicaForPrediction](https://github.com/antononcube/MathematicaForPrediction).
[1]: https://imgs.xkcd.com/comics/curve_fitting.png
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2018-10-09at1.14.45PM.png&userId=143837Anton Antonov2018-10-09T17:16:31ZHow can accurate measurements be made of angles found in an image?
http://community.wolfram.com/groups/-/m/t/520537
I am a materials scientist studying the microstructures of alloys of tungsten, iron, and nickel processed using liquid-phase sintering. The alloys produce microstructures full of spheroid tungsten particles, some of them connected to other particles, within a matrix of iron-nickel alloy. In places where two particles connect, they form a "neck" between them, which appears as a solid-solid boundary extending in two directions to "triple-points" where the solid-liquid boundaries of the surfaces of the respective connected particles both intersect. The angles formed by the respective orientations of the three intersecting boudaries are known in literature as "dihedral angles" and are indicative of the respective energies of the boundaries that form them. The relative differences in boundary surface energies has dominating effects on the evolution of the microstructures of these alloys through the processing/sintering time, and so it is important to have tools that can take automated measurements of them as they appear in digital micrographs so that large samples of measurements may be accumulated to provide a large sample and more accurate estimates of the population statistics.
I have developed Mathematica code that will binarize the grayscale images that I have, and refine these binary images so that they closely represent the shapes and contours of the surface boundaries of particles. Also, I have used the ImageCorners operation to identify the triple-points in the images with good success. This leaves me with the task of taking measurements of the angles at these triple points. Most of the discussion that I have seen so far involves measurements of angles at "branches" where vertexes are identified and numbered and then used to find the angles using the "VectorAngle" operation. This approach may work, but the closest that I have come to isolating branches in my images is by using the Perimeter function to make an image of just the pixels at the particle boundaries and their intersections. This leaves me with a bit of code left to do, and I am just starting out in Mathematica and not quite up to that task yet. Any help is appreciated.Phillip Green2015-06-30T00:28:07ZMathematica 11 on Raspberry Pi?
http://community.wolfram.com/groups/-/m/t/902162
I am very impressed with the functionalities that have been added to the new version 11 of Mathematica and I would love to use some of those in lessons I am preparing for students. Is anything known about plans to update Mathematica for Raspberry Pi to version 11? Because that is what the students use.Ted vanderTogt2016-08-10T06:09:57ZPlot Labels with arrows or lines pointing to different curves?
http://community.wolfram.com/groups/-/m/t/1503349
I'm trying to get plot labels with arrows or lines pointing to different curves. If I do
A2 = 1;
Plot[Evaluate@
Table[Labeled[Sqrt[x^2 - x^4]/Sqrt[
1 + A2 \[Beta]], \[Beta]], {\[Beta], {.1, .5, 1, 5, 10, 20}}], {x,
0, 1.2}, AxesLabel -> {Subscript[k, x], Subscript[k, y]},
PlotRange -> All, LabelStyle -> Directive[14, Bold]]
I get the following image.
![Dispersion relations][1]
How do I make the lines point to a better part of the curves?
I've also tried something along the lines of
Plot[Evaluate@
Table[Sqrt[x^2 - x^4]/Sqrt[
1 + \[Beta]], {\[Beta], {.1, .5, 1, 5, 10, 20}}], {x, 0, 1.2},
PlotLabels ->
Placed[{"\[Beta] = .1", "\[Beta] = .5", "\[Beta] = 1",
"\[Beta] = 5", "\[Beta] = 10", "\[Beta] = 20"}, Above],
PlotRange -> All]
I've tried using `Scaled[]` as well. Those options seem to move the labels around but remove the lines pointing to the curves.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Untitled.png&userId=1355889Derek Handwerk2018-10-09T22:39:39Z