a=matrix([[11,12,13,14],[21,22,23,24],[31,32,33,34],[41,42,43,44]])
a.add_multiple_of_row(1,1,-1,-1)
a.add_multiple_of_row(2,2,-1,-1)
a.add_multiple_of_row(3,3,-1,-1)
print a
print det(a)

* Radha Bhukya, student, SNIST * Usha Rani,student, SNIST