Re: How to evaulate a function and graph it
- To: mathgroup at smc.vnet.net
- Subject: [mg43225] Re: How to evaulate a function and graph it
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Wed, 20 Aug 2003 22:25:22 -0400 (EDT)
- References: <bht3hi$n22$1@smc.vnet.net>
- Reply-to: "Allan Hayes" <hay at haystack.demon.co.uk>
- Sender: owner-wri-mathgroup at wolfram.com
"Rebeca Choy" <rchoy at ula.ve> wrote in message news:bht3hi$n22$1 at smc.vnet.net... > Hi everyone, > > How can I evaluate a function of 2 variables, say: > > f(x,y) = x^4 + 3 x^2 + 5 y^2 + x + y > > in an interval of [-3.0,4.0] and[-3.0,4.3] for x and y? > > I need all the points between these two ranges to plot it > > > Thanks > > Rebeca > Rebeca, First, you need to use the correct syntax for defining a function: f[x_,y_] = x^4 + 3 x^2 + 5 y^2 + x + y Then we can calculate some (not all!) points in the range that you stipulate; vals = Table[ f[x, y], {x, -3.0, 4.0, .2}, {y, -0.0, 2, .2}]; and plot them: ListPlot3D[vals, MeshRange -> {{0, 2}, {-3, 4}} ] (MeshRange give the right ticks on the axes) though it the following is easier Plot3D[f[x, y], {x, 0, 2}, {y, -3, 4}] and we can do without defining the function Plot3D[x^4 + 3 x^2 + 5 y^2 + x + y, {x, 0, 2}, {y, -3, 4}] -- Allan --------------- Allan Hayes hay at haystack.demon.co.uk Voice: +44 (0)116 241 8747 Fax: +44 (0)870 164 0565