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RSS Feed for Wolfram Community showing any discussions in tag Algebra sorted by activeUnexpected results from Solve[ ]?
https://community.wolfram.com/groups/-/m/t/2250180
Hi
I am having some troubles using Solve. Specifically, I want to determine the intercept curve of two surfaces. I have two functions wh[n_, B_] and wh1[n, B], these functions are equal for n=10^5 and B=0.32. Nevertheless, when I set B=0.32 and I use Solve to calcule the intercept point, Solve doesn’t work properly, It shows an imaginary result when It should give n=10^5. Finally, in others examples the result of Solve is { }. Would you help me with these two problems?
Thank you in advance.
&[Wolfram Notebook][1]
[1]: https://www.wolframcloud.com/obj/73f2bd89-d042-4efa-b88a-fc713e476ba2Benny Rodríguez Saenz2021-04-22T05:56:04ZMatrix representation of a central finite difference scheme.
https://community.wolfram.com/groups/-/m/t/2250341
I am struggling to write a code for a central finite difference scheme in Mathematica. I need assistance identifying books, sites or videos that can get me started.Sam Rametse2021-04-22T11:56:21ZInconsistent results for inequality query
https://community.wolfram.com/groups/-/m/t/2249279
Hi All,
I've been trying to have Wolfram|Alpha help me out with some inequality calculations, but I can't seem to get consistent results. Here is an example. I'm looking for values that will give certain errors in this series, and when I use the variable n, I do get a list of possible values that meet the inequality:
![enter image description here][2]
Wanting a precise value, and thinking that the choice of variable may have had something to do with it, I put in x, however the answer is then wildly inaccurate (real answer 4<x<5 somewhere):
![enter image description here][1]
What could be happening here?
[1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=icr_1.png&userId=2248809
[2]: https://community.wolfram.com//c/portal/getImageAttachment?filename=icr_2.png&userId=2248809Shaun Olafson2021-04-21T05:34:48ZNMinimize not working on custom function?
https://community.wolfram.com/groups/-/m/t/2248727
When defining the values of suma[x] as regression function I 'm able to obtain te true values of suma[x], when entering x manually.
Nevertheless when I try to Nminimize suma[x] it seems that this finction does not take the value of x
I willl thank a lot any suggestion
Thanks
&[Wolfram Notebook][1]
[1]: https://www.wolframcloud.com/obj/3d03f9cc-d6fe-475f-bf32-262c139733c0rafael ibanez2021-04-20T16:52:27ZRepresent and compute with matrix-valued functions of a vector?
https://community.wolfram.com/groups/-/m/t/2247942
In the attachment I pose a problem of representing and computing with a matrix-valued function of a vector. Before I go to the effort of learning Mathematica, I would like to know that it can do these kinds of computations and yield results in the usual notation or something close to it. I would appreciate any guidance, including being told that my request is impossible. Thanks.Darwin Poritz2021-04-19T21:33:03ZLooking for a closed-form solution using Solve[ ]
https://community.wolfram.com/groups/-/m/t/2246994
I was wondering if a closed form solution does exist for the following equation:
a^2 Exp[x/a] + x^2/2 (1 - b) - a^2 - a x Exp[x/a] = 0
where a and b are Real numbers. I would like to obtain a solution of the form x=f(a,b).
I tried to use the following command:
Solve[a^2*Exp[x/a] + x^2/2*(1 - b) - a^2 - a*x*Exp[x/a] == 0, x,
Assumptions -> Element[a, Reals], Assumptions -> Element[b, Reals]]
but I obtained the following message: Solve: This system cannot be solved with the methods available to Solve.
I was wondering whether I could use the Lambert W function to solve this equation or if there is any way to obtain an approximated solution of this equation. I am looking for a solution for x<0, and I know that a>0, if this can make any difference.
Thank you.
**Edited after the 1st reply:**
The last sentence is probably superfluous: I am interested in the general closed-form solution of this equation. Then, I will use the part of solution when x<0 (which happens when 0<b<1).sebastiano piccolroaz2021-04-19T08:13:21Z