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Newbie Plot-Fit Questions.

• To: mathgroup at smc.vnet.net
• Subject: [mg31116] Newbie Plot-Fit Questions.
• From: realbeaux at yahoo.com (SkyBeaux)
• Date: Wed, 10 Oct 2001 19:14:35 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Please explain this to me:

If I do the following:

Fit[{{2942, 3650782}, {2955, 2255796}, {3204, 730421}, {4105,
1740135}, {7815,
       6329111}, {13097, 7116844}}, {1, x, x^2, x^3}, x]

Results are:
\!\(1.7044496230729986`*^7 - 8507.38287339198`\ x + 
    1.3901134594316935`\ x\^2 - 0.00006096360495406324`\ x\^3\)

Then I plot the results as follows:

\!\(Plot[1.7044496230729986`*^7 - 8507.38287339198`\ x + 
      1.3901134594316935`\ x\^2 - 0.00006096360495406324`\ x\^3, {x,
2942,
      13097}]\)

I get a nice "sin" looking plot.  (This is what I want.)

However if I try to combine the two statements into one.  Like this:

Plot[(Fit[{{2942, 3650782}, {2955, 2255796}, {3204, 730421}, {4105, 
          1740135}, {7815, 6329111}, {13097, 7116844}}, {1, x, x^2,
x^3},
      x]), {x, 2942, 13097}]

I get a linear chart.  

What is the difference?  And how do I get my nice "sin" looking plot
back?

As you can see, I an not really sure what is being plotted by the
first set of commands, but I think it is a log plot.

Thanks for you help.

--SB

• Follow-Ups:
  • Re: Newbie Plot-Fit Questions.
    • From: Tomas Garza <tgarza01@prodigy.net.mx>