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