|  |  7.10.6.26 ncrepIsDefined Procedure from libraryncrat.lib(see  ncrat_lib).
 
Example:Usage:
list l = ncrepIsDefined(q, vars, n, maxcoeff);
Return:
list(dim, list vars, list(A1, ..., Ak)), where:
If dim > 0 then there are matrices A1, ..., Ak of size dim
such that q is defined at A = (A1, ..., Ak), i.e.,
 q.mat is invertible at A.
 If dim = 0 then no such point was found.
 
Note:
Test whether q.mat is invertible via evaluation
at random matrix points with integer coefficients
 in [-maxcoeff, maxcoeff]. Stops after n tries.
 Use ixi-matrix in i-th try. The list vars contains the
 nc variables which occur in q.
 
 |  | LIB "ncrat.lib";
ncInit(list("x", "y"));
ncrat f = ncratFromString("inv(x*y-y*x)");
ncrep q = ncrepGet(f);
ncrepIsDefined(q, list(x, y), 5, 10);
==> [1]:
==>    2
==> [2]:
==>    [1]:
==>       x
==>    [2]:
==>       y
==> [3]:
==>    [1]:
==>       _[1,1]=0
==>       _[1,2]=-9
==>       _[2,1]=-2
==>       _[2,2]=7
==>    [2]:
==>       _[1,1]=8
==>       _[1,2]=-9
==>       _[2,1]=-4
==>       _[2,2]=-2
ncrat g = ncratFromString("inv(x-x)");
ncrep r = ncrepGet(g);
ncrepIsDefined(r, list(x), 5, 10);
==> [1]:
==>    0
==> [2]:
==>    [1]:
==>       x
==> [3]:
==>    empty list
 | 
 
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