On Wed, Mar 21, 2007 at 01:20:05PM -0700, Ben Pfaff wrote: > It already does support one-pass moments: use the moments1_* > functions instead of the moments_* functions.
Okay. 'sorry for not seeing them before. > > Second question: moments.c could also be made to compute correlations > > between variables in a single data pass. If changing it to do so > > doesn't make a mess of moments.c, does anyone mind if I make that > > modification, too? > > Is there a logical or computational reason why correlations > should be integrated into moments instead of being a separate > module? Computing correlations, means and variances at the same time would eleminate at least one data pass. But computing them at the same time also would introduce a structure (or matrix) in the moments struct to store the correlations for each pair of variables. I don't know if the added complexity would be worth the benefit of eleminating data passes. If moments.c doesn't have a way to compute correlations, then to avoid the extra data passes, any procedure that needs correlations will have to compute them on its own. -Jason _______________________________________________ pspp-dev mailing list [email protected] http://lists.gnu.org/mailman/listinfo/pspp-dev
