Re: Newbie Plot-Fit Questions.

*To*: mathgroup at smc.vnet.net*Subject*: [mg31122] Re: [mg31116] Newbie Plot-Fit Questions.*From*: BobHanlon at aol.com*Date*: Fri, 12 Oct 2001 03:36:39 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 2001/10/10 8:14:36 PM, realbeaux at yahoo.com writes: >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. > non\[Hyphen]standard way... You should use Evaluate to evaluate the function to be plotted if this can safely be done before specific numerical values are supplied." 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}]; Bob Hanlon Chantilly, VA USA