1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 #include "math/percentiles.h"
21 #include "data/casereader.h"
22 #include "data/val-type.h"
23 #include "data/variable.h"
24 #include "libpspp/assertion.h"
25 #include "libpspp/cast.h"
26 #include "math/order-stats.h"
28 #include "gl/xalloc.h"
31 #define _(msgid) gettext (msgid)
32 #define N_(msgid) msgid
35 percentile_calculate (const struct percentile *ptl, enum pc_alg alg)
37 struct percentile *mutable = CONST_CAST (struct percentile *, ptl);
38 const struct order_stats *os = &ptl->parent;
40 if (ptl->g1 == SYSMIS)
41 mutable->g1 = (os->k[0].tc - os->k[0].cc) / os->k[0].c_p1;
43 if (ptl->g1_star == SYSMIS)
44 mutable->g1_star = os->k[0].tc - os->k[0].cc;
46 if (ptl->g2 == SYSMIS)
49 mutable->g2 = os->k[1].tc / os->k[1].c_p1;
50 else if (os->k[1].c_p1 == 0)
53 mutable->g2 = (os->k[1].tc - os->k[1].cc) / os->k[1].c_p1;
56 if (ptl->g2_star == SYSMIS)
59 mutable->g2_star = os->k[1].tc;
60 else if (os->k[1].c_p1 == 0)
63 mutable->g2_star = os->k[1].tc - os->k[1].cc;
69 if (ptl->g1_star >= 1.0)
73 double a = (os->k[0].y == SYSMIS) ? 0 : os->k[0].y;
75 if (os->k[0].c_p1 >= 1.0)
76 return (1 - ptl->g1_star) * a + ptl->g1_star * os->k[0].y_p1;
78 return (1 - ptl->g1) * a + ptl->g1 * os->k[0].y_p1;
84 double a = (os->k[0].y == SYSMIS) ? 0 : os->k[0].y;
86 if (os->k[0].c_p1 >= 1.0)
87 return (ptl->g1_star < 0.5) ? a : os->k[0].y_p1;
89 return (ptl->g1 < 0.5) ? a : os->k[0].y_p1;
94 if (ptl->g1_star == 0)
101 if (ptl->g2_star >= 1.0)
103 return os->k[1].y_p1;
107 double a = (os->k[1].y == SYSMIS) ? 0 : os->k[1].y;
109 if (os->k[1].c_p1 >= 1.0)
111 if (ptl->g2_star == 0)
114 return (1 - ptl->g2_star) * a + ptl->g2_star * os->k[1].y_p1;
118 return (1 - ptl->g2) * a + ptl->g2 * os->k[1].y_p1;
125 if (ptl->g1_star == 0)
126 return (os->k[0].y + os->k[0].y_p1)/ 2.0;
128 return os->k[0].y_p1;
143 destroy (struct statistic *stat)
145 struct percentile *ptl = UP_CAST (stat, struct percentile, parent.parent);
146 struct order_stats *os = &ptl->parent;
153 percentile_create (double p, double W)
155 struct percentile *ptl = xzalloc (sizeof (*ptl));
156 struct order_stats *os = &ptl->parent;
157 struct statistic *stat = &os->parent;
166 os->k = xcalloc (2, sizeof (*os->k));
168 os->k[1].tc = (W + 1.0) * p;
170 ptl->g1 = ptl->g1_star = SYSMIS;
171 ptl->g2 = ptl->g2_star = SYSMIS;
173 os->k[1].y_p1 = os->k[1].y = SYSMIS;
174 os->k[0].y_p1 = os->k[0].y = SYSMIS;
176 stat->destroy = destroy;