Double integral where the limit of y is a function of x

Question

Wenjuan 2013-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/109298-double-integral-where-the-limit-of-y-is-a-function-of-x

评论： Andrei Bobrov 2013-12-11

I am trying to work out double integral, where the limit of y is a function of x, and the limits itself are vectors, like

n=1:10;
t=2;
a=(n-1).*t;
b=n.*t;
fun=@(x,y)lognpdf(b-x,2,1).*lognpdf(y,3,2);  
ymax=@(x) b-x;  
Qab=@(a,b)integral2(fun,a,b,0,ymax);  
Q=arrayfun(Qab,a,b);

but this returns error

Error using  - 
      Matrix dimensions must agree.
      Error in @(x)b-x

Is this because b is a vector?

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Walter Roberson 2013-12-10

Perhaps you should use the ArrayValued option of integral2() ?

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Answer 1

Andrei Bobrov 2013-12-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/109298-double-integral-where-the-limit-of-y-is-a-function-of-x#answer_117980

编辑：Andrei Bobrov 2013-12-11

在 MATLAB Online 中打开

EDIT

n=1:10;
t=2;
a=(n-1).*t;
b=n.*t;
[ai,y] = ndgrid(a,b);
bi = y.';
f = @(x,y,y2)logpdf(y2-x,2,1).*logpdf(y,3,2);
out = arrayfun(@(x1,y1,y2)integral2(@(x,y)f(x,y,y2),x1,y1,0,@(x)y2-x),ai,bi,y);