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B.7.0.12 IsCentral

Procedure from library nctools.lib (see nctools_lib).

Usage:
IsCentral(p,[v]); p poly, v an integer (with v!=0 procedure will be verbose)

Return:
integer (1 if p commutes with all variables, 0 otherwise)

Example:
 
LIB "nctools.lib";
ring r=0,(x,y,z),dp;
matrix D[3][3]=0;
D[1,2]=-z;
D[1,3]=2*x;
D[2,3]=-2*y;
ncalgebra(1,D); // this is U(sl_2)
poly c = 4*x*y+z^2-2*z;
IsCentral(c,0);
==> 1
poly h = x*c;
IsCentral(h,1);
==> Noncentral at: y
==> Noncentral at: z
==> 0


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            User manual for Singular version 2-1-99, August 2004, generated by texi2html.