Integral2 and anonymous function in a matrix

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Zaharaddeen Hussaini 2017-11-12

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评论： Zaharaddeen Hussaini 2017-11-13

I cannot seem to get integration over a function right. Any explanation why the section of code doesn't run. Even after changing ymax to scalar, matrix exceed dimension error is alway there.

lxx = 2 * RR;
lyy= RH.* cos(eT); % et is [35*6] matrix
sigma_tot = sqrt((D*(0.0045.^2+0.-0025.^2+sigma_bq.^2+0.0065.^2))); % sigma_tot returns a [35*6] matrix
fun = @(lx,ly) exp ( - ((lx.^2 + ly.^2)./(2*sigma_tot.^2)));
int_i = integral2(fun,0,lxx,0,lyy);

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Answer 1

Walter Roberson 2017-11-12

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You indicate that sigma_tot is 35 x 6, and fun uses sigma_tot so fun returns a 35 x 6 matrix.

Integral2 can only integrate scalar functions.

"The function fun must accept two arrays of the same size and return an array of corresponding values. It must perform element-wise operations."

To operate over the entire sigma_tot array to get a 35 x 6 output, you will need to arrayfun over sigma_tot:

fun = @(lx,ly, sigtot) exp ( - ((lx.^2 + ly.^2)./(2*sigtot.^2)));
int_i = arrayfun(@(sigtot) integral2( @(x,y) fun(x,y,sigtot),0,lxx,0,lyy), sigma_tot);

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Zaharaddeen Hussaini 2017-11-13

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Thanks. Had no idea Integral2 can only integrate scalar functions and would never have discovered arrayfun. I take it I do the same thing for argument lyy which is a also a matrix of equal size.

lyy= RH.* cos(eT); % et is [35*6] matrix

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