Stanislav, I'm afraid I don't have the time to investigate this case in
detail, but I do hope I've given you the information you need to investigate
it yourself.
-s
2010/1/7 Stanislav Maslovski <stanislav.maslovski at gmail.com>
> On Thu, Jan 07, 2010 at 06:01:03PM -0500, Stavros Macrakis wrote:
> > Not surprising. This expression:
> >
> > plot3d(cabs(f(ky,kz)),[ky,-3,3],[kz,-3,3]);
> >
> > means "calculate cabs(f(ky,kz)) as an argument to plot3d (without binding
> ky
> > and kz) -- call the result xxx; now evaluate xxx for various numeric
> values of
> > ky and kz". In other words, it first calculates a *symbolic expression*
> for
> > the absolute value, then evaluates that at various values. What you want
> to do
> > is presumably calculate the *numeric values* of f(ky,kz) at various
> values and
> > then take the cabs of that. You can do that with:
> >
> > plot3d( '( cabs(f(ky,kz)) ),[ky,-3,3],[kz,-3,3]);
> >
> > which should have the same effect as your plot3d(abs_f,...) expression.
>
> Sure. Then why
>
> plot3d(sqrt(realpart(subst(k0=%i,Ree)^2+imagpart(k0=%i,Ree)^2),...)
>
> still works (see the example I sent in my first mail)?
>
> --
> Stanislav
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