On Fri, 2006-11-24 at 13:08 +0100, Hugo Coolens wrote:
> On Fri, 24 Nov 2006, Miquel Cabanas wrote:
> > On Fri, 2006-11-24 at 12:02 +0100, Hugo Coolens wrote:
> >>
> >> Thanks for the quick reply, I changed the syntax as you suggested but
> >> entering zth[2]; gives:
> >>
> >> zth(1) s + 1
> >>
> >> ------------------
> >>
> >> (zth(1) + 1) s + 1
> >>
> >> and not:
> >>
> >> (1+2*s)/(1+3*s+s^2)
> >
> > try
> >
> > (%i12) radcan( zth[2] );
> >
> Even though the radcan function is available it doesn't do anything as you
> can see from the output below:
> radcan( zth[2] );
>
> zth(1) s + 1
> (%o89)
> ------------------
>
> (zth(1) + 1) s + 1
>
> Any idea what's wrong?
probably your insistence in using parentheses instead of brackets.
Compare your entries with the ones in the session below. BTW, I have set
DISPLAY2D to false only to ensure that the output isn't formatted and
that the message looks ok.
(%i5) DISPLAY2D : FALSE;
(%o5) FALSE
(%i6) zth[1] : 1/(1+s);
(%o6) 1/(s+1)
(%i7) zth[m] := (1+zth[m-1]*s)/(1+s*(1+zth[m-1]));
(%o7) zth[m]:=(1+zth[m-1]*s)/(1+s*(1+zth[m-1]))
(%i8) zth[2];
(%o8) (s/(s+1)+1)/(s*(1/(s+1)+1)+1)
(%i9) radcan(zth[2]);
(%o9) (2*s+1)/(s^2+3*s+1)
but
(%i10) zth(2);
(%o10) zth(2)
(%i11) radcan(zth(2));
(%o11) zth(2)
and the same happens if you incorrectly use parentheses in the
definitions.
Miquel