|  |  7.5.20.0. isInvertibleLeftFraction Procedure from libraryolga.lib(see  olga_lib).
 
Example:Usage:
isInvertibleLeftFraction(frac, locType, locData), vector frac,
int locType, list/vector/intvec locData
Purpose:
check if a fraction is invertible in the specified localization
Assume:
Return:
int
Note:
- returns 1, if the numerator of frac is in the denominator set,
- returns 0, otherwise (NOTE: this does NOT mean that the fraction is
not invertible, it just means it could not be determined by the
method above).
 |  | LIB "olga.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
poly g1 = x+3;
poly g2 = x*y;
list L = g1,g2;
vector frac = [g1*g2, 17, 0, 0];
isInvertibleLeftFraction(frac, 0, L);
==> 1
ideal p = x-1, y;
frac = [g1, x, 0, 0];
isInvertibleLeftFraction(frac, 1, p);
==> 1
intvec rat = 1,2;
frac = [g1*g2, Dx, 0, 0];
isInvertibleLeftFraction(frac, 2, rat);
==> 0
 | 
 
 |