For a pivoted algorithm, I have to perform an operation that in fully vectorized form can be expressed as: pivot = tableau[locat,:]/tableau[locat,cand] tableau -= tableau[:,cand:cand+1]*pivot tableau[locat,:] = pivot tableau is a rather large bidimensional array, and I'd like to avoid the allocation of a temporary array of the same size holding the result of the right-hand side expression in the second line of code (the outer product of tableau[:,cand] and pivot). On the other hand, if I replace that line with: for i in xrange(tableau.shape[0]): tableau[i] -= tableau[i,cand]*pivot ...I incur some CPU overhead for the "for" loop -- and this part of code is the botteneck of the whole algorithm. Is there any smarter (i.e., more time-efficient) way of achieving my goal? TIA -- Enzo