Re: double integral problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg112535] Re: double integral problem*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sun, 19 Sep 2010 05:37:33 -0400 (EDT)

I don't think you can expect to have Mathematica carry out a numerical integration when it involves a non-numeric quantity a. Try this, with the integration variables reversed: NIntegrate[Exp[-a/(4 x)-4 x]/.a->1,{Q,0,1},{x,0,Q}] On 9/18/2010 7:26 AM, Regina wrote: > hi there, > im trying to evaluate the following double integral: > N[Integrate[Integrate[Exp[-a/(4 x) - 4 x], {x, 0, Q}], {Q, 0, 1}]] > > and set a to 1 or some other non-zero number. > > but for some reason, mathematica only gives me error messages. what am > i doing wrong? > best. regina > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305