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Surface fitting question

• To: mathgroup at smc.vnet.net
• Subject: [mg38472] Surface fitting question
• From: Bob Priester <bpriester at stopthespam.org>
• Date: Wed, 18 Dec 2002 01:54:15 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

I have data in an ascii text file that consists of 26 rows and 17
colums of numbers.  I would like to fit a surface to the data in order
to get an equation for the contents of the table in terms of the
values that the rows and colums represent. I'm new to mathematica. So
far, this is what I've been able to do (not much):

data = Table[ReadList["curves.txt", Number, RecordLists -> True]];

ListPlot3D[data]

Then I see a plot of my real data (a surface). It looks correct. But I
can't figure out how to do the following:

1. get the real data values on the x & y axes. Ie, the x axis goes
from 0 to 17 and the y axis goes from 0 to 26. What I really need is
the x axis to be from 0.0 to 3.0 (but the steps are not evenly
spaced), and the y axis to go from 0 to 250.  At least the z axis (the
surface) is plotting like I need it.

2. I think that I'd need the real x and y arrays (not just use the
index)  for Fit[] to compute the correct answer.


Does anyone have a list of necessary commands to do this?

thanks,
Bob

• Follow-Ups:
  • Re: Surface fitting question
    • From: Tomas Garza <tgarza01@prodigy.net.mx>