[0,1] true if arr is central(i.e. all planes intersect in 0)
Note:
This is the same as homog(A)
Example:
LIB "arr.lib";
ring R = 0,(x,y,z),dp;
// centered and central
arr A = ideal(x,y,z);
arrCentered(A);
==> 1
arrCentral(A);
==> 1
// centered but not central (center: (-1,-1/2, 1))
arr B = ideal(x+1,2y+1,-z+1);
arrCentered(B);
==> 1
arrCentral(B);
==> 0