Re: RowReduce::luc when using NSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg99189] Re: RowReduce::luc when using NSolve*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 29 Apr 2009 06:38:34 -0400 (EDT)*Organization*: Uni Leipzig*References*: <gt6fkm$rru$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, NSolve[{BesselJ[0, 20] - BesselJ[0, 20] r[0] == 3 I BesselJ[0, 60 I] t[0], BesselJ[0, 20] + BesselJ[0, 20] r[0] == BesselJ[0, 60 I] t[0]}, {r[ 0], t[0]}, WorkingPrecision -> 30] ? Regards Jens mereandor wrote: > I try to solve a linear equation with the following input to mathematica: > > NSolve[{BesselJ[0, 20] - BesselJ[0, 20] r[0] == 3 I BesselJ[0, 60 I] t[0], BesselJ[0, 20] + BesselJ[0, 20] r[0] == BesselJ[0, 60 I] t[0]}, {r[0], t[0]}] > > but I get > > RowReduce::luc: Result for RowReduce of badly conditioned matrix \ > {{-0.167025+0. I,-1.61061*10^9-<<21>> I,0.167025+0. I},{<<1>>}} may \ > contain significant numerical errors. >> > > This is only the simplest instance of my problem (2(n+1) equations in equally numbered variables). If I don't write the equations down literally but insert them into NSolve as a Table[] statement I don't even get the warning. Then the equations are solved only partially expressing t[n] as linear combination of r[n]. > > I use Mathematica 6.0 > > How can I resolve this? > > Thanks in advance for any help! >