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D.3.1.7 is_complex
Procedure from library matrix.lib (see matrix_lib).
- Usage:
- is_complex(c); c = list of size-compatible modules or matrices
- Return:
- 1 if c[i]*c[i+1]=0 for all i, 0 if not, hence checking whether the
list of matrices forms a complex.
- Note:
- Ideals are treated internally as 1-line matrices.
If printlevel > 0, the position where c is not a complex is shown.
Example:
| | LIB "matrix.lib";
ring r = 32003,(x,y,z),ds;
ideal i = x4+y5+z6,xyz,yx2+xz2+zy7;
list L = nres(i,0);
is_complex(L);
==> 1
L[4] = matrix(i);
is_complex(L);
==> 0
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