How to evaluate definite integrals?

Log Out | Topics | Search Moderators | Register | Edit Profile

Author Message   shi liang (caleb_shi) Member Username: caleb_shi Post Number: 11 Registered: 12-2004 Posted on Monday, March 21, 2005 - 02:31 am:    Hi, Sir. does the flexPDE can evaluate the definite integral about a scalar variable? is there any example about that? The details of question is in the attached file. Thanks a lot! integral integral.doc (17.4 k)   Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 343 Registered: 06-2003 Posted on Monday, March 21, 2005 - 02:49 pm:    FlexPDE is not a general mathematical evaluation package. It is a finite element model builder for partial differential equations. As such, it expects to have a physical domain defined, and to create a mesh and a finite element model on that mesh. If your expression is merely an integral you wish to evaluate, you can do it by defining a fictitious physical domain over which to approximate the integrand, and then requesting an INTEGRAL(...). In FlexPDE version 4, there is no provision for one-dimensional domains, so you will have to create a strip, most conveniently 10 x 1, over which to do the evaluation. See the example "Samples | Misc | Funtest.pde" for a similar use of FlexPDE. If your integral is to be used as a parameter in a PDE problem, then use the above procedure or some other external method to create a table of integrals as a function of parameters, and import it into the PDE problem.