Re: Not a valid limit in NIntegrate ???

*To*: mathgroup at smc.vnet.net*Subject*: [mg3144] Re: Not a valid limit in NIntegrate ???*From*: whitic at rpi.edu (whitic)*Date*: Tue, 6 Feb 1996 22:51:03 -0500*Organization*: Rensselaer Polytechnic Institute, Troy NY, USA*Sender*: owner-wri-mathgroup at wolfram.com

a_kowald at chemie.fu-berlin.de (Axel Kowald) wrote: >Hi >FindRoot[NIntegrate[t,{t,rho,100}]==1,{rho,99}] >NIntegrate[t,{t,rho,100}] /. rho->99 >When I'm using one of the above constructs either on a Mac or under Unix >running Mathematica 2.2 I get the following error message: >NIntegrate::nlim: t=rho is not a valid limit of integration >Why does it complain ?? Any ideas ?? >Many thanks > Axel Kowald Try using the built in Secant method for the FindRoot routine. Mathematica uses this method when FindRoot is called with the following syntax: FindRoot[ f[x]==g[x], {x,x1,x2}] For the problem in question, you can use the command: FindRoot[ NIntegrate[t,{t,rho,100}]==1,{rho,99,100}] with this, Mathematica does not complain, since it does not have to evaluate, analytically the Jacobian of this numerical function. Hope this helps, Chris Whiting whitic at rpi.edu ==== [MESSAGE SEPARATOR] ====