5.1.48 imap

Syntax:

imap ( ring_name, name )

Type:

number, poly, vector, ideal, module, matrix or list (the same type as the second argument)

Purpose:

identity map on common subrings. imap is the map between rings and qrings with compatible ground fields which is the identity on variables and parameters of the same name and 0 otherwise. (See map for a description of possible mapping between different ground fields). Useful for mapping from a homogenized ring to the original ring or for mappings from/to rings with/without parameters. Compared with fetch, imap uses the names of variables and parameters. Unlike map and fetch imap can map parameters to variables.

Example:

ring r=0,(x,y,z,a,b,c),dp; ideal i=xy2z3a4b5+1,homog(xy2z3a4b5+1,c); i; → i[1]=xy2z3a4b5+1 → i[2]=xy2z3a4b5+c15 ring r1=0,(a,b,x,y,z),lp; ideal j=imap(r,i); j; → j[1]=a4b5xy2z3+1 → j[2]=a4b5xy2z3 ring r2=(0,a,b),(x,y,z),ls; ideal j=imap(r,i); j; → j[1]=1+(a4b5)*xy2z3 → j[2]=(a4b5)*xy2z3

See fetch; homog; map; qring; ring.