Singular Manual: isInvertibleNcfrac

| #### D.15.25.10 isInvertibleNcfrac Procedure from library `ncfrac.lib` (see ncfrac_lib). Usage: isInvertibleNcfrac(frac), ncfrac frac Purpose: checks if frac is invertible Return: int, 1 if frac is invertible, 0 otherwise Example:
    LIB "ncfrac.lib";
    ==> // ** redefining testNcfrac (LIB "ncfrac.lib";)
    ==> // ** redefining testNcloc (    LIB "ncloc.lib";)
    ==> // ** args must be 4 in     system("install", "ncloc", "string", nclocToS\
       tring, 1);
    ==> // ** args must be 4 in     system("install", "ncfrac", "string", ncfracT\
       oString, 1);
    ring R = 0,(x,y,Dx,Dy),dp;
    def S = Weyl();
    setring S;
    ncloc loc = intvec(2);
    ncfrac frac = list([y,y+1,0,0], loc);
    isInvertibleNcfrac(frac);
    ==> 1
    frac = list([y,x+1,0,0], loc);
    isInvertibleNcfrac(frac);
    ==> 0

User manual for Singular version 4-1-1p3, 2018, generated by texi2html.