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D.15.1.11 arrCentral

Procedure from library arr.lib (see arr_lib).

Usage:
arrCentral(A); arr A

Return:
[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
See also: arrCenter; arrCentered; arrCentral; arrCentralize.


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