On Mon, Aug 2, 2010 at 1:50 AM, Terry Reedy <tjre...@udel.edu> wrote: > On 7/30/2010 7:46 AM, Lawrence D'Oliveiro wrote: >> >> Say a vector V is a tuple of 3 numbers, not all zero. You want to >> normalize >> it (scale all components by the same factor) so its magnitude is 1. >> >> The usual way is something like this: >> >> L = math.sqrt(V[0] * V[0] + V[1] * V[1] + V[2] * V[2]) >> V = (V[0] / L, V[1] / L, V[2] / L) >> >> What I don’t like is having that intermediate variable L leftover after >> the >> computation. > > So, instead of fooling around with error-prone, hard-to-type constructions, > just delete the damn thing! > > def L
del L :P > > Compare those foolproof 5 chars to what at first did not work right and even > what did. And, as other said, in most real applications, you will normalize > in more than one place. In fact, you may well want a vlen function. > > def vlen(seq): return math.sqrt(sum(x*x for x in seq)) > > -- > Terry Jan Reedy > > > -- > http://mail.python.org/mailman/listinfo/python-list > -- Matteo Landi http://www.matteolandi.net/ -- http://mail.python.org/mailman/listinfo/python-list
