Error using .* Matrix dimensions must agree.

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Pradipta Panchadhyayee
评论： Dyuman Joshi 2023-11-25
Ran in:
clc; clear all;
den = @(x,y) x.^2 + y.^2;
A = @(x,y) 1./den(x,y);
[u,v] = meshgrid(-1:0.5:1,-1:0.5:1);
fun = @(x,y) (x.*u).*(y.*v).*A(x,y);
F = integral2(fun,0,1,0,1);
Arrays have incompatible sizes for this operation.

Error in solution>@(x,y)(x.*u).*(y.*v).*A(x,y) (line 6)
fun = @(x,y) (x.*u).*(y.*v).*A(x,y);

Error in integral2Calc>integral2t/tensor (line 228)
Z = FUN(X,Y); NFE = NFE + 1;

Error in integral2Calc>integral2t (line 55)
[Qsub,esub] = tensor(thetaL,thetaR,phiB,phiT);

Error in integral2Calc (line 9)
[q,errbnd] = integral2t(fun,xmin,xmax,ymin,ymax,optionstruct);

Error in integral2 (line 105)
Q = integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct);
Fp = F.*conj(F)*u.*v;
surf(u, v, Fp)
shading interp;
colormap jet
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Pradipta Panchadhyayee
Pradipta Panchadhyayee 2023-11-25
Thanks for your reply. F will be a function of only u and v when its will be integrated over x and y.

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采纳的回答

Walter Roberson
Walter Roberson 2023-11-25
integral2() passes in 2D arrays of variable but equal size to the function handle. For example one time it might pass in a pair of 14 x 14 arrays, and another time it might pass in 2 x 3 arrays.
fun = @(x,y) (x.*u).*(y.*v).*A(x,y);
Those arrays of arbitrary size do not happen to match up with the size of u or v
The function you pass to integral2() must return an array the same size as the inputs. It is completely invalid to try to return a mesh of points per x y pair .
I would point out that your u and v appear as local constants in the functions. You could substitute 1 for u and v and get out an scalar integral value, and then multiply that scalar result by u.*v to get the grid you were hoping to calculate.
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Pradipta Panchadhyayee
Pradipta Panchadhyayee 2023-11-25
@ Bring the definitions of den and A out of the loos as they are not varying with the loops.
Thanks for your reply. I admit. I take it a representative program. If I deal with long expressions of x and y in den and A the runtime is increased with loop structures. But making this change the runtime becomes same as before. I want to get rid of loops if there is another way to make runtime error minimum.
@ There's no need of defining C1 and C2 in the loop, nor are you using the variables afterwards in the code, so remove those two lines.
I admit. I was checking with long expressions of x and y in den and A and checking with which speed the values are calculated. That's why I used C1 and C2 in the loop.
Dyuman Joshi
Dyuman Joshi 2023-11-25
"But making this change the runtime becomes same as before."
No, There will definitely be a change in runtime.
"I was checking with long expressions of x and y in den and A and checking with which speed the values are calculated. That's why I used C1 and C2 in the loop."
This makes no sense, atleast to me.
Did you make the changes I said and then compared the runtime speed?

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更多回答（1 个）

Paul
Paul 2023-11-25
The anonymous function fun won't work unless the input arguments x and y are compatible for elementwise-multiplication with u and v respectively. That's unlikely to be the case with fun is called from integral2 and probably isn't what you want even if it were. Can you explain or show mathemetically what F is supposed to be?
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Pradipta Panchadhyayee
Pradipta Panchadhyayee 2023-11-25
Thanks for your reply. F will be a function of only u and v when its will be integrated over x and y.

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