Re: A 3D Plot Query
- To: mathgroup at smc.vnet.net
- Subject: [mg94249] Re: A 3D Plot Query
- From: Helen Read <read at math.uvm.edu>
- Date: Tue, 9 Dec 2008 06:56:47 -0500 (EST)
- References: <ghj01t$ff8$1@smc.vnet.net>
pcoords29 at gmail.com wrote:
> Hi,
>
> This may sound silly, but I can't get it to work. (I'm using v 6.0)
>
> How do I get my 3D plots look as given in textbooks, ie. with the y-
> axis pointing to the right, the z-axis up and x-axis pointing out of
> the paper/screen ( showing the first octant)? I mean the kind of
> plots one draws on paper when working out surface integrals in
> Calculus classes.
The default ViewPoint for Plot3D is ViewPoint -> {1.3, -2.4, 2.}
Use ViewPoint -> {1.3`, 2.4`, 2.`} will give you the view that you are
used to (x-axis point out, y-axis point to the right).
> If this is of any help, I'd like to get the plot of the paraboloid
>
> z = 2-(x^2+y^2), as given in Fig. 10-10 of Spiegel's Advanced
> Calculus, Schaum Series.
This is a separate issue. See below.
> I tried
>
> Plot3D[2 - (x^2 + y^2), {x, -a, a}, {y, -a, a}],
>
> with various values of a. Unfortunately, none of them look like the
> traditional cap-shaped paraboloid.
Is this what you are going for?
Plot3D[2 - (x^2 + y^2), {x, -2, 2}, {y, -2, 2},
RegionFunction -> Function[{x, y, z}, 0 <= x^2 + y^2 <= 4]]
And if you want the first octant, oriented the way you draw it on the board:
Plot3D[2 - (x^2 + y^2), {x, 0, 2}, {y, 0, 2},
RegionFunction -> Function[{x, y, z}, 0 <= x^2 + y^2 <= 4],
ViewPoint -> {1.3`, 2.4`, 2.`}]
--
Helen Read
University of Vermont