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Wolfram Language Optimization Numerical Computation

FindMaximum failing

ash ash

Posted 10 years ago

Hi all.. I am trying to find the maximum point for the following graph.. it is visually clear that it is around 1300.. I was wondering whats the command for it... Is it FindMaximum [{Cp[[Delta]]}, {[Delta], 0, 1}]]? i tried this and it dint work .. Any help would help.. Thanks in advance..

POSTED BY: ash ash

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ash ash

Posted 10 years ago

Sorry in the first hand. yes! i missed to paste the [Mu]m , i was only not sure with the command to be used. may be i should read the posting guidelines.. i am only learning mathematica. is there a rule that i cannot ask basic or east questions in this forum?

POSTED BY: ash ash

ash ash

Posted 10 years ago

but thanks it helped. i was only asking if FindMaximum would work.. it worked when i wrote it after plot syntax.

POSTED BY: ash ash

W. Craig Carter

W. Craig Carter, MIT

Posted 10 years ago

Hello Ash Ash, I am sorry if my response appeared to be rude to you. It was not my intention. Danny is correct that the probability of getting a response is increased if code can be cut-and-pasted from the post. I believe that basic questions should be encouraged. However, if the poster makes an effort (to fix syntax, look for a working example in the documentation, and make sure that all variables which be defined are defined), that effort will be rewarded by learning.

POSTED BY: W. Craig Carter

ash ash

Posted 10 years ago

Thanks.. I just have a follow up question.. What would be the command in case if delta is known.. for example, delta = 0.3 and I need to get the corresponding y axis value..

POSTED BY: ash ash

W. Craig Carter

W. Craig Carter, MIT

Posted 10 years ago

Hello Ash Ash, Perhaps I misunderstand your question. I am assuming that you are no longer interested in a maxima. To find the value of an expression for a particular value of a parameter, you can use slash-dot with a rule: expr = a Cos[ b x] expr /. a -> 2 expr /. {a -> 2, x -> 3} expr /. {a -> 2, b -> 3, x -> Pi} More information can be found here: tutorial/ApplyingTransformationRules

POSTED BY: W. Craig Carter

ash ash

Posted 10 years ago

thanks! that was clarifying! :)

POSTED BY: ash ash

W. Craig Carter

W. Craig Carter, MIT

Posted 10 years ago

Hello, While at risk of encouraging those who do not read the posting guidelines or the documentation.... Pn = 40; \[Mu]p = 0.2; cp = -Pn ( 0.066 (56250.` \[Delta]^2 + 24496.` \[Delta] \[Mu]m - 18723.` \[Delta]^2 \[Mu]m - 480.` \[Mu]m^2 + 540.` \[Delta] \[Mu]m^2 - 135.` \[Delta]^2 \[Mu]m^2))/(\[Delta] (168.` \[Delta] - 9.` \[Delta]^2 + 160.` \[Mu]m - 180.` \[Delta] \[Mu]m + 45.` \[Delta]^2 \[Mu]m)) (\[Delta] - 1)/\[Mu]p temp = cp /. \[Mu]m -> 1 Plot[temp, {\[Delta], 0, 1}] FindMaximum[temp, \[Delta]] with hopes that I can get someone to look at my CUDA questions on community.... sigh. WCC

Hello, While at risk of encouraging those who do not read the posting guidelines or the documentation....

Pn = 40;
\[Mu]p = 0.2;
cp = -Pn (
  0.066 (56250.` \[Delta]^2 + 24496.` \[Delta] \[Mu]m - 
     18723.` \[Delta]^2 \[Mu]m - 480.` \[Mu]m^2 + 
     540.` \[Delta] \[Mu]m^2 - 
     135.` \[Delta]^2 \[Mu]m^2))/(\[Delta] (168.` \[Delta] - 
     9.` \[Delta]^2 + 160.` \[Mu]m - 180.` \[Delta] \[Mu]m + 
     45.` \[Delta]^2 \[Mu]m)) (\[Delta] - 1)/\[Mu]p
temp = cp /. \[Mu]m -> 1
Plot[temp, {\[Delta], 0, 1}]
FindMaximum[temp, \[Delta]]

with hopes that I can get someone to look at my CUDA questions on community.... sigh. WCC

POSTED BY: W. Craig Carter

Daniel Lichtblau

Daniel Lichtblau, Wolfram Research

Posted 10 years ago

(1) Post actual code with the question. A picture of code is not a usable substitute. (2) From the notebook I can see there is an undefined `\[Mu]m` (as well as an unused `\[Mu]p`). (3) The `Solve` syntax is incorrect. While this is not a forum for issues of basic Mathematica syntax, I will remark that you get no output because the input never reaches the stage of evaluation. (4) You define `Cp` as a function of a dummy variable delta. Also it has `Np`which uses a delta in its definition. But these are not the same because it is not that dummy variable: you have a scoping problem. Here is what I mean. Cp[t] (* Out[21]= -(( 13.2 (-1 + t) (56250. \[Delta]^2 + 24496. \[Delta] \[Mu]m - 18723. \[Delta]^2 \[Mu]m - 480. \[Mu]m^2 + 540. \[Delta] \[Mu]m^2 - 135. \[Delta]^2 \[Mu]m^2))/(\[Delta] (168. \[Delta] - 9. \[Delta]^2 + 160. \[Mu]m - 180. \[Delta] \[Mu]m + 45. \[Delta]^2 \[Mu]m))) *)

POSTED BY: Daniel Lichtblau

ash ash

Posted 10 years ago

I pasted the picture, only to show what i really want to ask. in this case the syntax to be used.. 3) is there even a rule that i cannot ask basic or easy questions in this forum?? in that case, it is a pity for beginners .