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7.7.3.0. inCenter
Procedure from library central.lib (see central_lib).
- Usage:
- inCenter(E); E poly/list/ideal
- Return:
- integer, 1 if E is in the center, 0 otherwise
- Purpose:
- check whether the elements of E are central
Example:
| | LIB "central.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;
def r = nc_algebra(1,D); setring r; // this is U(sl_2)
poly p=4*x*y+z^2-2*z;
inCenter(p);
==> 1
poly f=4*x*y;
inCenter(f);
==> 0
list l= list( 1, p, p^2, p^3);
inCenter(l);
==> 1
ideal I= p, f;
inCenter(I);
==> 0
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