Here are some suggested changes to the linear_least_squares function. Colin W. Lines 571 ownward are: resids = num.array([],type=t) if one_eq: x = copy.copy(num.ravel(bstar)[:n]) if (results['rank']==n) and (m>n): resids = num.array([num.sum((num.ravel(bstar)[n:])**2)]) else: x = copy.copy(num.transpose(bstar)[:n,:]) if (results['rank']==n) and (m>n): resids = copy.copy(num.sum((num.transpose(bstar)[n:,:])**2)) resids= bstar return x,resids,results['rank'],copy.copy(s[:min(n,m)]) Line 571 should probably read: resids = None as no information is available if n >= m, probably the common case. Line 580 should be deleted, as it returns misleading information. For the n > m cases it would probably be good to return: (b - a * x).var(0), where the function var(0) delivers a row vector containing the column variances.