Re: Double integration results in "error: quad: invalid recursive call"

[Afsshl]

according the method you use in colloc() in last email, I change my variable x, y to rsin(theta), rcos(theta), it indeed make problem become 2 independent variable if I chose to integrate on a circle (area not perimeter) radius 3, so f= 9x^2 -3z

 

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octave:1> function z=f(x,y)
>                  z= (9* x^2 * (sin(y)^2) - 3 * x * cos(y)) * x;
> endfunction
octave:2> n=1; [r,A,B,q]=colloc(n); r*=3; r+=0; q*=2*pi; q'*f(r,r')*q
ans = 1174.3
octave:3>

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but that is not the answer, which should be 572.555

 

any comment?

eric