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Re: Newbie Question -- Plot3d::plnc

• To: mathgroup at smc.vnet.net
• Subject: [mg52781] Re: Newbie Question -- Plot3d::plnc
• From: "nguyen.longson at gmail.com" <nguyen.longson at gmail.com>
• Date: Mon, 13 Dec 2004 04:22:30 -0500 (EST)
• References: <cpav9n$isv$1@smc.vnet.net><cpekan$736$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

You can do what you want by typing these commands instead

xtimesy = x*y;
Plot3D[xtimesy, {x, -5, 5}, {y, -5, 5}]

Function Plot3D doesn't consider the first argument as a function, but
as a list of values of xtimesy at the specified values of x and y (the
values that you defined by {x, -5, 5}, {y, -5, 5}

Cheers,


Helen Read wrote:
> jujubaby at gmail.com wrote:
> > X-No-Archive: Yes
> >
> > When I enter the following two statements into Mathematica 5:
> >
> > xtimesy[x_, y_] := x*y;
> > Plot3D[xtimesy[x y], {x, -5, 5}, {y, -5, 5}]
> >
> > I receive a huge cascade of errors, all of this form:
> >
> > Plot3D::plnc: xtimesy[x\y] is neither a machine-size real number at
\
> > {x,y}={-5.,-5.} nor a list of a real number and a valid color
> > directive.
> >
> > What am I doing wrong?
>
> Should be
>
> xtimesy[x_, y_] := x*y;
> Plot3D[xtimesy[x,y], {x, -5, 5}, {y, -5, 5}]
> 
> --
> Helen Read
> University of Vermont

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