       Re: Newbie Plot-Fit Questions.

• To: mathgroup at smc.vnet.net
• Subject: [mg31126] Re: Newbie Plot-Fit Questions.
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 12 Oct 2001 03:36:43 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <9q2l22\$p4d\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

Plot[] has the attribute HoldAll and you have to enclose
an argument by Evaluate[] if you wish to evaluate it  and

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

work as expected.

Regards
Jens

SkyBeaux wrote:
>
> 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

```

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