Re: Constructing polynomials

[Justin Walker <justin@mac.com>]

Thanks, Karim,

I guess I have to plead guilty to aggravated density...

On Jul 22, 2004, at 1:18, Karim Belabas wrote:

> * Justin Walker [2004-07-22 04:53]:
[snip]
> > In psuedo-code terms, I'd like to do something like
> >
> > MyProc(a,b)=
> > {
> >     f(x)=(x+a)^b;
> >     for (i=1,limit, print(f(i)));
> > }
> >
> > Is this (a) feasible; (b) not easy; (c) Forgetaboutit?
>
> Why not:
>
>   MyProc(a,b)=
>   {
>     f=(x+a)^b;
>     for (i=1,limit, print(subst(f, x, i)));
>   }

I did try this, but I was working with 't_SER', and subst groused at 
me: "non polynomial or series type substituted in a series".  I could 
make
   subst(f,x,0*x)
work, but that's somewhat limited :-}.  Is it possible to 'evaluate' a 
series at a constant in pari/gp?

> ? If you insist on defining a user function, then you can use
>
>   MyProc(a,b)=
>   {
>     ( f(x) = (x+a)^b );
>     for (i=1,limit, print(f(i)));
>   }
>
> [ which is more efficient using the standard GP parser ]

This, I'd never have figured out.  For my purposes, it is the better 
alternative.

Why do the "()"s make it acceptable?

Thanks for your help!

Regards,

Justin

--
Justin C. Walker, Curmudgeon-At-Large  *
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