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How to draw double integral functions

  1. Feb 14, 2012 #1
    Hi every one!

    I would like to draw a double integral function in related to R and h parameters by below M-File but It does goes wrong!!!
    Is there any one to correct it for me???
    thank you

    syms R h;

    a1 = 0;

    a2 = atan(R./(R+h));

    r1 = h;
    r2 = sqrt(R.^2+(R+h).^2);

    integrand = @(r,a)(h.*sin(a)/((r.^2).*(r.^2+h.^2-2.*r.*h.*cos(a))));
    f = quad2d(integrand,r1,r2,a1,a2);

    ezsurf(f,[0.001,5]);
     
  2. jcsd
  3. Feb 14, 2012 #2

    kai_sikorski

    User Avatar
    Gold Member

    There's two problems that I can see right away (and perhaps more that I don't see). For one I'm guessing you're trying to make f a function of R and h? But you just leave them as symbolic objects. The second problem is that where you define the integrand, you need an extra "."

    Code (Text):
    integrand = @(r,a)(h.*sin(a)./((r.^2).*(r.^2+h.^2-2.*r.*h.*cos(a))));

    If I understand what you're trying to do correctly then this should do it:
    Code (Text):

    f = @(h,R) quad2d(@(r,a)(h.*sin(a)./((r.^2).*(r.^2+h.^2-2.*r.*h.*cos(a)))),h,sqrt(R.^2+(R+h).^2),0,atan(R./(R+h)));
    ezsurf(f,[0.001,5]);
     
    When I ran it, there were a bunch of warnings but I think that may be due to a singularity in the integral you're evaluating.
     
  4. Feb 15, 2012 #3
    Thank you very much.

    your correctness lets the functions be drawn!!!!!
     
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