D.5.6.2 invunit

Procedure from library mondromy.lib (see mondromy_lib).

Usage:

invunit(u,n); u poly, n int

Assume:

The polynomial u is a series unit.

Return:

The procedure returns the series inverse of u up to order n or a zero polynomial if u is no series unit.

Display:

The procedure displays comments if printlevel>=1.

Example:

LIB "mondromy.lib";
ring R=0,(x,y),dp;
invunit(2+x3+xy4,10);
→ 1/8x2y8-1/16x9+1/4x4y4+1/8x6-1/4xy4-1/4x3+1/2