Re: How to eliminate the big-oh

[Bill Allombert <allomber@math.u-bordeaux.fr>]

On Wed, Dec 11, 2002 at 02:26:13PM -0500, Michael Somos wrote:
> Franck Michel writes :
> 
> > but truncate(taylor((1-x)/(1-t),t)) does not eliminate the big-oh. 
> 
> True, but :
> 
> ? print(truncate(taylor((1-t)/(1-x)+O(x^5),x)))  
> (-t + 1)*x^4 + (-t + 1)*x^3 + (-t + 1)*x^2 + (-t + 1)*x + (-t + 1)
> 
> may be what you are looking for. Perhaps if you give an example of
> desired output we could give an expression to produce it. Shalom,

As Michael say, x has an higher priority than t and truncate only truncate with
respect of the highest priority variable.

This is a problem here.
Assuming z has higher priority that x, you can do

subst(truncate(subst(taylor((1-x)/(1-t),t),x,z)),z,x)

fortunately there is a  simpler solution, convert your polynomial to a vector:

Pol(truncate(Vec(taylor((1-x)/(1-t),t))))

Cheers,
Bill.