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D.15.26.1 isDenom
Procedure from library ncloc.lib (see ncloc_lib).
- Usage:
- isDenom(p, loc), poly a, ncloc loc
- Purpose:
- check if p is a valid denominator in the localization loc
- Return:
- int
- Note:
- returns 1 or 0, depending whether p is a valid denominator
Example:
| | LIB "ncloc.lib";
==> // ** redefining testNcloc (LIB "ncloc.lib";)
ring R = 0,(x,y,Dx,Dy),dp;
def S = Weyl();
setring S; S;
==> // coefficients: QQ
==> // number of vars : 4
==> // block 1 : ordering dp
==> // : names x y Dx Dy
==> // block 2 : ordering C
==> // noncommutative relations:
==> // Dxx=x*Dx+1
==> // Dyy=y*Dy+1
// monoidal localization
ncloc loc;
poly g1 = x^2*y+x+2;
poly g2 = y^3+x*y;
list L = g1,g2;
loc = L;
poly g = g1^2*g2;
poly f = g - 1;
isDenom(g, loc);
==> 1
isDenom(f, loc);
==> 0
// geometrical localization
loc = ideal(x-1,y-3);
g = x^2+y-3;
f = (x-1)*g;
isDenom(g, loc);
==> 1
isDenom(f, loc);
==> 0
// rational localization
intvec v = 2;
loc = v;
g = y^5+17*y^2-4;
f = x*y;
isDenom(g, loc);
==> 1
isDenom(f, loc);
==> 0
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