5.1.124 subst

Syntax:

subst ( poly_expression, ring_variable, poly_expression )
subst ( vector_expression, ring_variable, poly_expression )
subst ( ideal_expression, ring_variable, poly_expression )
subst ( module_expression, ring_variable, poly_expression )

Type:

poly, vector, ideal or module (corresponding to the first argument)

Purpose:

substitutes a ring variable by a polynomial.

Example:

ring r=0,(x,y,z),dp; poly f=x2+y2+z2+x+y+z; subst(f,x,3/2); → y2+z2+y+z+15/4 int a=1; subst(f,y,a); → x2+z2+x+z+2 subst(f,y,z); → x2+2z2+x+2z subst(f,y,z+1); → x2+2z2+x+4z+2

See ideal; map; module; poly; vector.