Re: NSolve problem
- To: mathgroup at smc.vnet.net
- Subject: [mg59296] Re: NSolve problem
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
- Date: Fri, 5 Aug 2005 01:21:24 -0400 (EDT)
- Organization: Uni Leipzig
- References: <dcsc67$q0k$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
you have 3 equations and two unknowns ?? This can
only
have a solution, when one of the 3 equations is
linear
depend on one of the others.
For exact numbers Mathematica can find the linear
depend equation
for inexact numbers you will get problems with the
precision.
In your case it may be the best to remove one of
the
equations
Solve[{2 x + 3 y == 8 + I 7.,
-2 I x + (1 + 3 I) y == 3 + 5 I}, {x, y}]
Regards
Jens
"Enrique Zeleny" <ezeleny at fcfm.buap.mx> schrieb im
Newsbeitrag news:dcsc67$q0k$1 at smc.vnet.net...
|
|
| Hi
| I f I try to solve these equations
|
| Solve[{2 x + 3 y == 8 + I 7,
| 3 x + y == 5 + 7 I, -2 I x + (1 + 3 I) y ==
3 + 5 I}]
|
| the result is
|
| {{x -> 1 + 2*I, y -> 2 + I}}
|
| but if I have
|
| Solve[{2 x + 3 y == 8 + I 7,
| 3 x + y == 4.99999999999999 + 7 I, -2 I x +
(1 + 3 I) y == 3 + 5 I}]
|
| gives
|
| \!\(\*FormBox[
| RowBox[{\(RowReduce::"luc"\), \(\(:\)\(\ \)\),
"\<\"Result for \
| \\!\\(TraditionalForm\\`RowReduce\\) of badly
conditioned matrix \
| \\!\\(TraditionalForm\\`\\((\[NoBreak]
\\(\[LeftSkeleton] 1 \
| \[RightSkeleton]\\) \[NoBreak])\\)\\) may
contain significant numerical \
| errors. \\!\\(\\*ButtonBox[\\\"More\\\",
| ButtonStyle->\\\"RefGuideLinkText\\\
| \", ButtonFrame->None,
ButtonData:>\\\"General::luc\\\"]\\)\"\>"}], \
| TraditionalForm]\)
|
|
| {}
|
|
| I need only an aproximate result, say 5 digits
of precission, how can I
| override the NSolve behavior?
|
|
| Thanks in advance
|