Re: Fitting Explicit Functions
- To: mathgroup at smc.vnet.net
- Subject: [mg6815] Re: Fitting Explicit Functions
- From: Stephen P Luttrell <luttrell at signal.dra.hmg.gb>
- Date: Mon, 21 Apr 1997 02:02:41 -0400 (EDT)
- Organization: Defence Research Agency
- Sender: owner-wri-mathgroup at wolfram.com
> I would like to fit some data to an implicit function. I have data for x and y
> for the following equation:
>
> 1/x = exp( b*y/x ).
>...
Solve your equation for y:
Solve[1/x == Exp[b y/x ],y]
gives the output
{{y -> (x*Log[1/x])/b}}
which tells you how y depends on x.
Now fit the function x*Log[1/x] to the data you supplied:
Fit[{{0.5, -0.693147}, {1., 0.}, {2., 2.7759}, {3, 6.592}}, x*Log[1/x],
x]
gives the output
-2.000354764236932*x*Log[1/x]
which tells you that b=-0.5 (approximately).
=============================================================================
Dr Stephen P Luttrell luttrell at signal.dra.hmg.gb
Adaptive Systems Theory 01684-894046 (phone)
Room EX21, Defence Research Agency 01684-894384 (fax)
Malvern, Worcs, WR14 3PS, U.K.
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