Singular Manual: SDLoc

| ##### 7.5.5.0. SDLoc Procedure from library `dmodapp.lib` (see dmodapp_lib). Usage: SDLoc(I, f); I an ideal, f a poly Return: ring (basering extended by a new variable) containing an ideal 'LD' Purpose: compute a generic presentation of the localization of D/I w.r.t. f^s Assume: the basering D is a Weyl algebra over a field of characteristic 0 Note: Activate this ring with the `setring` command. In this ring, the ideal LD (given as Groebner basis) is the presentation of the localization. Display: If printlevel =1, progress debug messages will be printed, if printlevel>=2, all the debug messages will be printed. Example:
    LIB "dmodapp.lib";
    ring r = 0,(x,y,Dx,Dy),dp;
    def R = Weyl(); // Weyl algebra on the variables x,y,Dx,Dy
    setring R;
    poly F = x2-y3;
    ideal I = Dx*F, Dy*F;
    // note, that I is not holonomic, since it's dimension is not 2
    gkdim(I);  // 3, while dim R = 4
    ==> 3
    def W = SDLoc(I,F);
    setring W; // = R[s], where s is a new variable
    LD;        // Groebner basis of s-parametric presentation
    ==> LD[1]=3*x*Dx*s+2*y*Dy*s-6*s^2+6*s
    ==> LD[2]=3*y^2*Dx*s+2*x*Dy*s
    ==> LD[3]=y^3*Dy-x^2*Dy-3*y^2*s+3*y^2
    ==> LD[4]=y^3*Dx-x^2*Dx+2*x*s-2*x

User manual for Singular version 4-1-3, 2020, generated by texi2html.