Singular Manual: isZeroFraction

| ##### 7.5.21.0. isZeroFraction Procedure from library `olga.lib` (see olga_lib). Usage: isZeroFraction(frac), vector frac Purpose: determine if the vector frac represents zero Assume: frac is a valid fraction Return: int Note: returns 1, if frac == 0; 0 otherwise Example:
    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
    isZeroFraction([42,0,0,0]);
    ==> 1
    isZeroFraction([0,0,Dx,3]);
    ==> 0
    isZeroFraction([1,1,1,1]);
    ==> 0

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