Re: [Maxima-discuss] Extracting the constant from a sum of exponentials

[Richard F. <fa...@gm...>]

In some sense this is not the constant coefficient.  If z = exp(%i*x) then
the expression is

v: (z^18-2*z^16-z^14+4*z^12-z^10-2*z^8+z^6)/(64*z^12)

note the denominator.

If you are seeking the term(s) in the expression that do not depend on x
[or z] , consider

taylor(v,z,0, 10);

which is  (I added spaces here for emphasis ...)

1/(64*z^6)-1/(32*z^4)-1/(64*z^2)  +           1/16         -
 z^2/64-z^4/32+z^6/64+...

RJF






On Sun, Jan 2, 2022 at 8:47 AM Michel Talon <ta...@lp...> wrote:

>
> Le 02/01/2022 à 17:34, Eduardo Ochs a écrit :
> > but I don't know how to extract the constant term - i.e., how to
> > obtain the coefficient of exp(0*%i*x)... these things don't work:
> >
> >   coeff(g, exp(0*%i*x));
> >   coeff(g, x, 0);
> >   coeff(g, 1);
>
> (%i5) ratcoeff(g,exp(%i*x),0);
>                                           1
> (%o5)                                 --
>                                           16
>
>
> --
> Michel Talon
>
>
>
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