Re: FindFit Mathematica 7
- To: mathgroup at smc.vnet.net
- Subject: [mg113924] Re: FindFit Mathematica 7
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 18 Nov 2010 07:05:16 -0500 (EST)
$Version
"7.0 for Mac OS X x86 (64-bit) (February 19, 2009)"
I also get the 1/0 error with
FindFit[{{0., 1.}, {1., -1}},
{a x + b, b == 0}, {a, b}, x]
However, in addition to your workaround, these work
FindFit[{{0., 1.}, {1., -1}},
a x + b /. b -> 0, {a, b}, x]
{a -> -1., b -> 0.}
FindFit[{{0., 1.}, {1., -1}},
a x, {a, b}, x]
{a -> -1., b -> 0.}
Fit[{{0., 1.}, {1., -1}}, x, x]
-1. x
Bob Hanlon
---- Derivator <derivatorb at gmail.com> wrote:
=============
Hi. I have a question regarding the use of constraints in FindFit.
In the version 6 the following command
FindFit[{{0., 1.}, {1., -1}}, {a x + b, b==0}, {a, b}, x]
yields a -> -1, b -> 0 (b==0 is a constraint).
I find in the version 7 that the same command produces an error of
the type 1/0.
Of course I still could use something like
FindFit[{{0., 1.}, {1., -1}}, {a x + b, Abs[b] < 0.001}, {a, b}, x]
or
With[{b=0},FindFit[{{0., 1.}, {1., -1}}, {a x + b}, {a}, x]
but this is not very natural. Is this a bug or is there a way around?
Regards
L.L.