This command selects some columns of an NCMatrix.
i1 : A = QQ{a,b,c,d} o1 = A o1 : NCPolynomialRing |
i2 : M = ncMatrix {{a,b,c,d},{b,c,d,a}} o2 = | a b c d | | | | b c d a | o2 : NCMatrix |
i3 : N = M || 2*M || -3*M o3 = | a b c d | | | | b c d a | | | | 2a 2b 2c 2d | | | | 2b 2c 2d 2a | | | | -3a -3b -3c -3d | | | | -3b -3c -3d -3a | o3 : NCMatrix |
i4 : N_{0,2} o4 = | a c | | | | b d | | | | 2a 2c | | | | 2b 2d | | | | -3a -3c | | | | -3b -3d | o4 : NCMatrix |