# Singular

#### D.15.18.25 grrndmap

Procedure from library `gradedModules.lib` (see gradedModules_lib).

Usage:
grrndmap(S,D), graded objects S and D

Return:

Purpose:
construct a random 0-deg graded homomorphism src(S) -> src(D)

Example:
 ```LIB "gradedModules.lib"; ring r=32003,(x,y,z),dp; module D=grobj(module([y,0,z],[x2+y2,z,0]),intvec(0,1,0)); grview(D); ==> Graded homomorphism: r + r(-1) + r <- r(-1) + r(-2), given by a matrix, w\ ith degrees: ==> ..1 ..2 .... ==> --- --- +... ==> 0 : 1 2 |..1 ==> 1 : - 1 |..2 ==> 0 : 1 - |..3 ==> === === ==> 1 2 module S=grobj(module([x,0,y],[xy,zy+x2,0]),intvec(0,0,0)); grview(S); ==> Graded homomorphism: r^3 <- r(-1) + r(-2), given by a matrix, with degree\ s: ==> ..1 ..2 .... ==> --- --- +... ==> 0 : 1 2 |..1 ==> 0 : - 2 |..2 ==> 0 : 1 - |..3 ==> === === ==> 1 2 def H=grrndmap(D,S); grview(H); ==> Graded homomorphism: r(-1) + r(-2) <- r(-1) + r(-2), given by a square ma\ trix, with degrees: ==> ..1 ..2 .... ==> --- --- +... ==> 1 : 0 1 |..1 ==> 2 : - 0 |..2 ==> === === ==> 1 2 ```