Re: the graphic of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg92092] Re: the graphic of a function*From*: "David Park" <djmpark at comcast.net>*Date*: Sat, 20 Sep 2008 04:56:10 -0400 (EDT)*References*: <gavt0r$g5a$1@smc.vnet.net>

Let's first define the function (instead of putting the full expression inside each plot statement). Note that we use square brackets and a pattern variable on the left hand side. f[x_] := x^2/(x + 1)^2 Then you can just plot as follows: Plot[f[x], {x, -10, 10}] However, much depends on precisely what domain you wish to include and what aspect of the function you wish to show. You will often need to use options in the plot statement. For example, Mathematica automatically picks what it thinks is the 'most interesting' PlotRange for a function and this will often not be what you desire. So if you only wanted to show the function for positive x you would have to specify the PlotRange to obtain a reasonable plot. Plot[f[x], {x, 0, 100}, PlotRange -> {0, 1}] If you wanted a domain that contained negative x values, you might prefer to use a Frame to get the y axes and its tick values off of the curve. (Technical publication almost always use Frame plots instead of Axes plots.) Here is one possible plot. Plot[f[x], {x, -10, 10}, Frame -> True, Axes -> False, PlotRange -> {0, 10}, PlotRangePadding -> {{Automatic, Automatic}, {1, .1}}] The point here is that Options are very important for plotting, although they may at first be difficult for new users. You can find out about graphics options by going to the Documentation Center, Visualization and Graphics, Options & Styling. It is also possible to find all the options for a function, say for Plot, by evaluating: Options[Plot] // Column Then you can find out about any particular option by putting the cursor after the symbol and pressing F1, -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Serg" <edy13ro20000 at yahoo.com> wrote in message news:gavt0r$g5a$1 at smc.vnet.net... >i think i've asked this before. anyway, i am new in mathematica and i want >how can I create the graphic of an exact function the same as I do for >Sin[]. > > for example f(x)=x^2/(x+1)^2 > can anyone help? >