integral2 error, bu the function works

fun = @(x,y) 1-exp(-0.01*norm(x-y));
q = integral2(fun,0,1,0,1);

It gives me the following error:

Error using integral2Calc>integral2t/tensor (line 241)
Integrand output size does not match the input size.

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 106)
    Q = integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct);

Error in IntegrateTriangularRegionwithSingularityattheBoundaryExample (line 19)
q = integral2(fun,0,1,0,ymax)

The function fun is well defined and tested. Work for both scalar and vector.

How to make the integral work?

[SL: edited to format code]

Answer 1

[Steven Lord]

What does the integral2 function require of the integrand function you specify as its first input?

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

What does your function do?

fun = @(x,y) 1-exp(-0.01*norm(x-y));
x = 1:10;
y = x+1;
z = fun(x, y)

Is z the same size as x and y? I think something closer to what you want is:

fun = @(x,y) 1-exp(-0.01*abs(x-y));
x = 1:10;
y = x+1;
z = fun(x, y)

[Xiangyu Meng]

I want to calculate the integral of the function fun in the planar [0,1]*[0,1].

[Torsten]

As Steven suggested, replace "norm" with "abs" in your function definition.

Best wishes

Torsten.

Answer 2

[Carlos Guerrero García]

A sketch of the function:

[x,y]=meshgrid(0:0.01:1); % The region in the statement
surf(x,y,1-exp(-0.01*abs(x-y))); % Plotting the surface
shading interp % For a nice view

and the integral can be calculated as follows:

syms x y; int(int(1-exp(-0.01*abs(x-y)),0,1),0,1)

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