D.3.2.3 inverse_L

Procedure from library linalg.lib (see linalg_lib).

Usage:

inverse_L(A); A = square matrix

Return:

list Inv representing a left inverse of A, i.e
- Inv[1] = matrix I and
- Inv[2] = poly p
such that I*A = unitmat(n)*p;

Note:

p=1 if 1/det(A) is computable and p=det(A) if not;
the computation computes first det(A) and then uses lift

Example:

LIB "linalg.lib";
ring r=0,(x,y),lp;
matrix A[3][3]=x,y,1,1,x2,y,x,6,0;
print(A);
list Inv=inverse_L(A);
print(Inv[1]);
print(Inv[2]);
print(Inv[1]*A);

See also: inverse; inverse_B.