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5.1.123 prune_map
Syntax:
prune_map( module_expression , smatrix_name )
Type:
- module
Purpose:
- returns the module minimally embedded in a free module such that the
corresponding factor modules are isomorphic together with the map
(as matrix)
Note:
- If for the input module the attribute
"isHomog" is
set, prune also sets the attribute "isHomog" .
For non-global orderings, only reduction steps with constant units are
performed. Hence, the returned module does not need to be minimal.
Example:
| ring r=0,(x,y,z),dp;
module m=gen(1),gen(3),[x,y,0,z],[x+y,0,0,0,1];
smatrix M;
print(m);
==> 1,0,x,x+y,
==> 0,0,y,0,
==> 0,1,0,0,
==> 0,0,z,0,
==> 0,0,0,1
print(prune_map(m,M)); // pruned module
==> v[1]:1 v[2]:1 v[3]:2 v[4]:2 v[5]:3
==> y,
==> z
print(m*M); // apply map
==> 0,
==> y,
==> 0,
==> z,
==> 0
print(M); // map
==> -x,
==> 0,
==> 1,
==> 0
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See
module.
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