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D.15.1.11 arrCentral
Procedure from libraryarr.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)
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 |