# Numerical volume integral with keeping parameters

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dont panic on 9 Sep 2013
HI ,
I wanted to calculate the magnetic potential of a bar magnet by numerical integration of the potential of a point source over the volume of the magnet. Below is my source code but I always get an error message.
a=0.0025; L=0.005; phis=0;
r1=0; r2=a; phi1=0; phi2=2*pi; z1=-L/2; z2=L/2;
%Function
f=@(r,phi,z,R,Z) (sin(phis-phi).*r)/(R.^2-2.*r.*R.*cos(phis-phi)+r.^2+(Z-z).^2).^(3/2);
[R,Z] = meshgrid(-0.05:s:0.05); mp=zeros(size( R ));
for k = 1:numel( R )
g = @(r,phi,z) f(r,phi,z,R(k),Z(k));
end
surf(R,Z,mp)

Mike Hosea on 11 Sep 2013
Well, for starters, you need to change / to ./ in the definition of f. Second, however, you will need to use integral3 instead of triplequad.
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Mike Hosea on 11 Sep 2013
Sorry, on second thought, you may not need INTEGRAL3. When I ran this, all I got were answers that numerically were not distinguishable from zero, and there is a singularity when R=0 and Z=0. There must be something wrong with your formulation.