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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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; User manual for <a href="http://www.singular.uni-kl.de/"><i>Singular</i></a> version 2-0-4, October 2002,
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