Re: Log(ln) Function + 2 Parameters + Greater

*To*: mathgroup at smc.vnet.net*Subject*: [mg89276] Re: Log(ln) Function + 2 Parameters + Greater*From*: "David Park" <djmpark at comcast.net>*Date*: Tue, 3 Jun 2008 06:44:35 -0400 (EDT)*References*: <g22tp5$ikl$1@smc.vnet.net>

First, define your f function with a as a parameter. f[a_][x_] := x (a + Log[x])^2 Mathematica can't make a plot unless it knows values for a. Of course, it won't plot any results for x < 0 and I'm not certain if you actually meant x > 0 rather than a > 0. In any case, you can use any real domain for a. Here is a plot for a specific value of a. Plot[f[2][x], {x, -5, 5}, AxesLabel -> {x, f}] You can look at an extended a domain by using Plot3D. Plot3D[f[a][x], {a, -5, 5}, {x, 0, 5}, PlotRange -> All, AxesLabel -> {a, x, f}] Another approach is to use a Manipulate statement with a controlled by a slider. Manipulate[ Plot[f[a][x], {x, 0, 5}, PlotRange -> {0, 250}, AxesLabel -> {x, f}], Style[Row[{HoldForm[f["a"][x]] == f["a"][x]}], 16], Delimiter, {a, -5, 5, Appearance -> "Labeled"}] -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Felipe Mannshardt" <vexie.infamous at googlemail.com> wrote in message news:g22tp5$ikl$1 at smc.vnet.net... > Hello, > > i am having problem telling Mathematica to: > > First Try, > > Clear[x, f] > f[x_] := x (a + Log[x])^2 > > a > 0 > Plot[f[x], {x, -5, 5}] > > Second Try, > > f[x_] := x (a + Log[x])^2 > > Plot[f[x], {x, -5, 5}] /.a-> a>0 > > > What i want is to tell Mathematica to draw a Graph of f[x] when a>0 > > Thanks for the help. >