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D.4.2.12 nonZeroEntry
Procedure from library algebra.lib (see algebra_lib).
- Usage:
- nonZeroEntry(id); id=object for which the test 'id[i]!=0', i=1,..,N,
N=size(id) (resp. ncols(id) for id of type ideal or module)
is defined (e.g. ideal, vector, list of polynomials, intvec,...)
- Return:
| a list, say l, with l[1] an integer, l[2], l[3] integer vectors:
- l[1] number of non-zero entries of id
- l[2] intvec of size l[1] with l[2][i]=i if id[i] != 0
in case l[1]!=0 (and l[2]=0 if l[1]=0)
- l[3] intvec with l[3][i]=1 if id[i]!=0 and l[3][i]=0 else
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- Note:
Example:
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