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7.10.6.27 ncrepIsRegular
Procedure from library ncrat.lib (see ncrat_lib).
- Usage:
- list l = ncrepIsRegular(q, vars, n, maxcoeff);
- Return:
- list(k, list vars, list(a1, ..., ak)), where:
If k = 1 then there are scalars (1x1-matrices) a1, ..., ak
such that q is defined at a = (a1, ..., ak), i.e.,
q.mat is invertible at a.
If k = 0 then no such point was found.
- Note:
- Test whether q.mat is invertible via evaluation
at random integers in [-maxcoeff, maxcoeff].
Stops after n tries. The list vars
contains the nc variables which occur in q.
Example:
| | LIB "ncrat.lib";
ncInit(list("x", "y"));
ncrat f = ncratFromString("inv(x*y-y*x)");
ncrep q = ncrepGet(f);
ncrepIsRegular(q, list(x, y), 10, 100);
==> [1]:
==> 0
==> [2]:
==> [1]:
==> x
==> [2]:
==> y
==> [3]:
==> empty list
ncrat g = ncratFromString("inv(1+x*y-y*x)");
ncrep r = ncrepGet(g);
ncrepIsRegular(r, list(x, y), 10, 100);
==> [1]:
==> 1
==> [2]:
==> [1]:
==> x
==> [2]:
==> y
==> [3]:
==> [1]:
==> _[1,1]=-55
==> [2]:
==> _[1,1]=-24
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