From 922dfe227e0a157f895c025b8f8590e2bfc59f23 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 29 Jan 2022 10:52:49 -0800
Subject: [PATCH] math: Avoid unneeded extra allocations for fixed-size data
 structures.

This seems generally a bit cleaner to me.
---
 src/math/percentiles.c  | 4 +---
 src/math/percentiles.h  | 2 ++
 src/math/trimmed-mean.c | 4 +---
 src/math/trimmed-mean.h | 2 ++
 src/math/tukey-hinges.c | 7 ++-----
 src/math/tukey-hinges.h | 1 +
 6 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/src/math/percentiles.c b/src/math/percentiles.c
index b43fed4616..1b4ff13632 100644
--- a/src/math/percentiles.c
+++ b/src/math/percentiles.c
@@ -139,8 +139,6 @@ static void
 destroy (struct statistic *stat)
 {
   struct percentile *ptl = UP_CAST (stat, struct percentile, parent.parent);
-  struct order_stats *os = &ptl->parent;
-  free (os->k);
   free (ptl);
 }
 
@@ -159,7 +157,7 @@ percentile_create (double p, double W)
   ptl->w = W;
 
   os->n_k = 2;
-  os->k = xcalloc (2, sizeof (*os->k));
+  os->k = ptl->k;
   os->k[0].tc = W * p;
   os->k[1].tc = (W + 1.0) * p;
 
diff --git a/src/math/percentiles.h b/src/math/percentiles.h
index 7af157b230..86fd641add 100644
--- a/src/math/percentiles.h
+++ b/src/math/percentiles.h
@@ -44,6 +44,8 @@ struct percentile
 
   double g2;
   double g2_star;
+
+  struct k k[2];
 };
 
 /* Create the Pth percentile.
diff --git a/src/math/trimmed-mean.c b/src/math/trimmed-mean.c
index b643651a26..4840fd2d66 100644
--- a/src/math/trimmed-mean.c
+++ b/src/math/trimmed-mean.c
@@ -44,8 +44,6 @@ static void
 destroy (struct statistic *s)
 {
   struct trimmed_mean *tm = UP_CAST (s, struct trimmed_mean, parent.parent);
-  struct order_stats *os = &tm->parent;
-  free (os->k);
   free (tm);
 }
 
@@ -57,7 +55,7 @@ trimmed_mean_create (double W, double tail)
   struct statistic *stat = &os->parent;
 
   os->n_k = 2;
-  os->k = xcalloc (2, sizeof (*os->k));
+  os->k = tm->k;
 
   assert (tail >= 0);
   assert (tail <= 1);
diff --git a/src/math/trimmed-mean.h b/src/math/trimmed-mean.h
index baa84bc24e..8803a127bc 100644
--- a/src/math/trimmed-mean.h
+++ b/src/math/trimmed-mean.h
@@ -32,6 +32,8 @@ struct trimmed_mean
 
   double w;
   double tail;
+
+  struct k k[2];
 };
 
 struct trimmed_mean * trimmed_mean_create (double W, double c_min);
diff --git a/src/math/tukey-hinges.c b/src/math/tukey-hinges.c
index aaf4881afa..b59b878ba6 100644
--- a/src/math/tukey-hinges.c
+++ b/src/math/tukey-hinges.c
@@ -64,10 +64,7 @@ static void
 destroy (struct statistic *s)
 {
   struct tukey_hinges *th = UP_CAST (s, struct tukey_hinges, parent.parent);
-  struct order_stats *os = &th->parent;
-
-  free (os->k);
-  free (s);
+  free (th);
 };
 
 struct tukey_hinges *
@@ -81,7 +78,7 @@ tukey_hinges_create (double W, double c_min)
   assert (c_min >= 0);
 
   os->n_k = 3;
-  os->k = xcalloc (3, sizeof (*os->k));
+  os->k = th->k;
 
   if (c_min >= 1.0)
     {
diff --git a/src/math/tukey-hinges.h b/src/math/tukey-hinges.h
index 4b509da1d4..5a6e079509 100644
--- a/src/math/tukey-hinges.h
+++ b/src/math/tukey-hinges.h
@@ -25,6 +25,7 @@
 struct tukey_hinges
 {
   struct order_stats parent;
+  struct k k[3];
 };
 
 struct tukey_hinges * tukey_hinges_create (double W, double c_min);
-- 
2.30.2