Re: Basic plotting of an evaluated function

*To*: mathgroup at smc.vnet.net*Subject*: [mg86912] Re: Basic plotting of an evaluated function*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 26 Mar 2008 04:52:11 -0500 (EST)*Organization*: Arcor*References*: <fsa5cd$ab2$1@smc.vnet.net>

Hi, it would be helpful a) if you would consider to read the manual b) use correct Mathematica syntax because NMinimize[{f[x,y],y=995,y=989},y] is remarkable nonsense anyway f[x_?NumericQ, y_?NumericQ] := x*(990 - y^2) s[x_?NumericQ] := y /. Last[NMinimize[{f[x, y], y < 995, y > 989}, y]] Plot[s[x], {x, -14, 46}] Regards Jens lederer at ssb.rochester.edu wrote: > I am trying to do something basic--but I cannot figure it out > > > I have some function in two varaibles > > f[x_,y_]= some arbitrary polynomial > > Now I want to minimize the function with respect to y over some > compact interval with fixed x > > NMinimize[{f[x,y],y=995,y=989},y] > > I want to plot the y's versus the x's. > > I have tried many things like defining > > s[x_]=Part[NMinimize[{f[x,y],y=995,y=989},y],2] > > Plot[s[x],{x,-14, 46}] > > or variations > > Plot[tt/.s[x],{x,-14, 46}]. > > Many error messages or nothing at all results......... > > I am sure this is easy, and someone can suggest how to do this. > > However, one more thing would be greatly helpful (give a man a decent > and readable Mathematica manual and he can feed himself...) > > I am baffled by what Mathematica wants when it comes to using a single > part of a list and changing it to a scalar. Suppose as above q is a > vector with a rule assigning a value to some variable x that is x- >> some number, and this assignment is in the third position of the list > > What is going on with q/.d[[3]] for example: Is q now a scalar? If > not why not? > > Thanks for you help, > > Phil Lederer >