# [Maxima] how to assume function value

Richard Fateman fateman at cs.berkeley.edu
Tue Jun 19 22:37:01 CDT 2007

Ratsubst would be better if you also want exp(4*omega*t)  etc to be zero.
But so is exp(omega*t).   Or did you want exp(n*omega*t) to be zero for n>2,
In which case you should expand in a taylor series in exp(omega*t).

RJF

> -----Original Message-----
> From: maxima-bounces at math.utexas.edu
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Daniel Lakeland
> Sent: Tuesday, June 19, 2007 7:59 PM
> To: maxima at math.utexas.edu
> Subject: Re: [Maxima] how to assume function value
>
> On Tue, Jun 19, 2007 at 07:14:17PM +0000, Andrew Pinsky wrote:
> > Hi!
> >
> > I have very long and complicated differential equation. I
> need to assume (set)
> > that any expression multiplied by exp(2*omega*t) is equal
> to zero. i.e. drop all
> > terms of this equation, that is multiplied by exp(2*omega*t).
> >
>
> use "subst" to substitute 0 for that expression:
>
> (%i1) eqn: exp(2*omega*t)*foo + bar;
>                                    2 omega t
> (%o1)                        foo %e          + bar
> (%i2) subst(0,exp(2*omega*t),eqn);
> (%o2)                                 bar
>
>
>
> --
> Daniel Lakeland
> dlakelan at street-artists.org
> http://www.street-artists.org/~dlakelan
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>