Rework moments routines for improved numerical stability based on

[pspp-builds.git] / src / ChangeLog

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+Sun Apr 11 14:22:12 2004  Ben Pfaff  <blp@gnu.org>
+
+       Rework moments routines for improved numerical stability based on
+       Michael Kiefte's advice.  Any bugs or remaining numerical problems
+       are still mine though.
+
+       There is now a struct moments1 for use with one-pass moments.  It
+       uses a provisional means algorithm as an attempt to improve
+       accuracy of higher moments.  The older struct moments now only
+       handles two-pass moments.
+       
+       * aggregate.c: Use moments1 instead moments.
+
+       * descript.c: Revert previous change, which is no longer needed
+       due to the moments revision.
+
+       * moments.c: (calc_moments) New function for calculating variance,
+       skewness, kurtosis.
+       (moments_pass_one) Only accumulate weights bigger than zero.
+       (moments_calculate) Allow calculating the mean on pass one, others
+       require pass two.  Implement in terms of calc_moments().
+       (struct moments1) New structure.
+       (init_moments1) New function.
+       (moments1_clear) Ditto.
+       (moments1_create) Ditto.
+       (moments1_add) Ditto.
+       (moments1_calculate) Ditto.
+       (moments1_destroy) Ditto.
+       (cmd_debug_moments) Deal with `struct moments' or `struct
+       moments1' as requested by user.
+
+Sun Apr 11 14:21:55 2004  Ben Pfaff  <blp@gnu.org>
+
+       * Makefile.am (pspp_SOURCES): Remove debug.c.
+
+       * debug.c: Removed.  It was empty anyway.
+
 Fri Apr  9 20:04:49 2004  Ben Pfaff  <blp@gnu.org>
 
        * descript.c (calc_descriptives): Fix assert failure when only