Infinite or Not-a-Number function value encountered.

2013 8 20
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Originally I tried to calculate
int(int((sin(q*A*sin(phi)/2)*sin(q*B*sin(phi)/2)*4/(q^2*A*B*sin(phi)*cos(phi)))^2*sin(q*C*cos(theta)/2)*2/(C*q))^2*sin(theta),theta,0,pi/2),phi,0.pi/2)
however MATLAB fail to show proper equation. So I change to use 'quad' function instead of 'int'
I just put A=B=C=7 and q=0.1 and tried to calculate...but failed. How can I calculate this equation?
-(183750365601059840*sin((7/20*sin(phi))).^4)./(8477503880968187*sin(phi).^2.*(sin(phi).^2. - 1) --> this equation comes from int((sin(q*A*sin(phi)/2)*sin(q*B*sin(phi)/2)*4/(q^2*A*B*sin(phi)*cos(phi)))^2*(sin(q*C*cos(theta)/2)*2/(C*q))^2*sin(theta),theta,0,pi/2) and put A, B, C, q values.
------------------------------------------------------------------------------------------
quad(@(phi) -(183750365601059840*sin((7/20*sin(phi))).^4)./(8477503880968187*sin(phi).^2.*(sin(phi).^2. - 1)),0.0001,pi/2)
Warning: Infinite or Not-a-Number function value encountered.
> In quad at 109
ans =
NaN

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David Sanchez
David Sanchez 2013-8-20

0 个投票

Besides the parenthesis unbalanced, you are dividing by zero.
for phi = pi/2
(8477503880968187*sin(phi)).^2.*(sin(phi).^2. - 1) = 0
Then:
r=-(183750365601059840*sin((7/20*sin(phi))).^4)/...
(8477503880968187*sin(phi)).^2.*(sin(phi).^2. - 1)
will yield NaN.

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