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D.15.1.12 arrCentered

Procedure from library arr.lib (see arr_lib).

Usage:
arrCentered(A); arr A

Return:
[0,1] true if A is centered(i.e. intersection of all planes not empty)

Note:
The algorithm uses the rank of matrix: Ax=b has a solution iff rank(A) = rank(A|b)

Example:
 
LIB "arr.lib";
ring R = 0,(x,y,z),dp;
arr A= ideal(x,y,x-y+1);        // centerless
arrCentral(A);
==> 0
arr B= ideal(x,y,z);            // central with center being the origin
arrCentral(B);
==> 1
arr C= ideal(x+1,2y+1,-z+1);    // central with center (-1,-1/2, 1)
arrCentral(C);
==> 0
See also: arrCenter; arrCentered; arrCentral; arrCentralize.


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