       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>

```Hi,

NSolve[{BesselJ[0, 20] - BesselJ[0, 20] r ==
3 I BesselJ[0, 60 I] t,
BesselJ[0, 20] + BesselJ[0, 20] r == BesselJ[0, 60 I] t}, {r[
0], t}, 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 == 3 I BesselJ[0, 60 I] t, BesselJ[0, 20] + BesselJ[0, 20] r == BesselJ[0, 60 I] t}, {r, t}]
>
> 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!
>

```

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