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Re: Problem with NIntegrate
Posted:
Aug 22, 2012 2:25 AM


Maybe i'm getting rusty with integration but since this is a triple integral with the limits of one variable defined in terms of another, you should change the order of integration a bit so that the integral with respect to Z evaluates before R. Maybe that will help.
So it is NIntegrate[....,{\[phi],...,..},{Z,...,...},{R,...,...}]
Chris
maves a écrit : > Hello, I'm trying to numerically integrate a complicated expression and Mathematica keeps showing plenty of error messages, such as > "NIntegrate::slwcon:Numerical integration converging too slowly; /.../", > "NIntegrate::eincr: The global error of the strategy GlobalAdaptive has increased more than 2000 times./../" and so on. If I only want to see the spatial distribution of the solution (contour plots in different planes etc.) , it somehow manages to come to an end, but the problem is that I need to use this solution in NDSolve, so it would take too long for the program to find the root. > > One of the problematic integrals is for instance > > NIntegrate[ > R (x  R Cos[\[Phi]] )/((x  R Cos[\[Phi]] )^2 + (y  > R Sin[\[Phi]] )^2 + (0  Z)^2)^(3/2), {\[Phi], 0, 2 Pi}, {R, > b, b + c}, {Z, R  (b + c), R + (b + c)} > > Any idea what is "wrong" with the integrand so that I get all these error messages? > > >



