Justin Walker on Thu, 22 Jul 2004 18:38:54 +0200

 Re: Constructing polynomials

```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?

```                                       |  It's whether *I* win or lose.