Using quad_qags



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   Date: Wed, 1 May 2013 15:03:38 -0500
   From: Ben Blomberg <bblomberg at mail.bradley.edu>
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   Hello All,

   I am trying to use the quad_qags function to evaluate the following with
   respect to x:

   P0:(quad_qags(v[1,1]*exp((-%i)*(10)*phi/(0.00197))*x,x,-0.63,0.63));

   phi is a variable i have in there for plotting purposes later on in the
   code.

   And v is calculated from the following sum:

   for n:1 thru 11 do for j:1 thru 21 do
   v[n,j]:1/sqrt(0.63)*(sum(vectors[n,j][m+11]*exp(%i*2*%pi*m*x/.63),m,-10,10));

   vectors is a list with values between 1*10^-6 and 1*10^-7.

   When I try this  I do not get the result with the list of the four
   elements. Instead I get a list of values that still contain x followed by
   the parameters esprel, epsabs and limit. I do not receive an error message
   but no value either. I tried this with quad_qag as well and had the same
   problem.

   Any thoughts on how to get a value?

   Thanks!
   Ben

Ben, the integrate command is quite capable of integrating P0
symbolically. So, you could do something like

define(P(phi,a,b), integrate(...,x,a,b));

where ... is your integrand above and your domain of integration is
the interval [a,b].

plot2d(P(phi,-0.63,0.63),[phi,-1,1]);

will then do what you want.

Leo