1 /* $NetBSD: mra.c,v 1.7 2018/03/10 23:25:59 khorben Exp $ */
2
3 /*
4 * Copyright (c) 1999 Shin Takemura All rights reserved.
5 * Copyright (c) 1999 PocketBSD Project. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 */
29
30 #include <sys/cdefs.h>
31 __KERNEL_RCSID(0, "$NetBSD: mra.c,v 1.7 2018/03/10 23:25:59 khorben Exp $");
32
33 #include <sys/param.h>
34 #include <sys/systm.h>
35
36 extern int mra_Y_AX1_BX2_C(const int *, int,
37 const int *, int, const int *, int, int, int,
38 int *, int *, int *);
39
40 /*
41 * multiple regression analysis
42 * Y = AX1 + BX2 + C
43 */
44 int
mra_Y_AX1_BX2_C(const int * y,int ys,const int * x1,int x1s,const int * x2,int x2s,int n,int scale,int * a,int * b,int * c)45 mra_Y_AX1_BX2_C(const int *y, int ys,
46 const int *x1, int x1s, const int *x2, int x2s,
47 int n, int scale,
48 int *a, int *b, int *c)
49 {
50 int i;
51 int64_t X1a, X2a, Ya;
52 int64_t X1X1s, X2X2s, X1X2s;
53 int64_t YYs, X1Ys, X2Ys;
54 int64_t S11, S22, S12;
55 // int64_t SYY;
56 int64_t S1Y, S2Y;
57 int64_t A, B, C, M;
58 #define AA(p, s, i) (*((const int *)(((const char *)(p)) + (s) * (i))))
59 #define X1(i) AA(x1, x1s, i)
60 #define X2(i) AA(x2, x2s, i)
61 #define Y(i) AA(y, ys, i)
62
63 /*
64 * get average and sum
65 */
66 X1a = 0; X2a = 0; Ya = 0;
67 X1X1s = 0; X2X2s = 0; X1X2s = 0;
68 X1Ys = 0; X2Ys = 0; YYs = 0;
69 for (i = 0; i < n; i++) {
70 X1a += X1(i);
71 X2a += X2(i);
72 Ya += Y(i);
73
74 X1X1s += X1(i) * X1(i);
75 X2X2s += X2(i) * X2(i);
76 X1X2s += X1(i) * X2(i);
77
78 X1Ys += X1(i) * Y(i);
79 X2Ys += X2(i) * Y(i);
80 YYs += Y(i) * Y(i);
81 }
82 X1a /= n; X2a /= n; Ya /= n;
83
84 S11 = X1X1s - n * X1a * X1a;
85 S22 = X2X2s - n * X2a * X2a;
86 S12 = X1X2s - n * X1a * X2a;
87
88 // SYY = YYs - n * Ya * Ya;
89 S1Y = X1Ys - n * X1a * Ya;
90 S2Y = X2Ys - n * X2a * Ya;
91
92 #if 0
93 printf("X1a=%d X2a=%d Ya=%d\n", (int)X1a, (int)X2a, (int)Ya);
94 printf("X1X1s=%d X2X2s=%d X1X2s=%d\n", (int)X1X1s, (int)X2X2s, (int)X1X2s);
95 printf("X1Ys=%d X2Ys=%d YYs=%d\n", (int)X1Ys, (int)X2Ys, (int)YYs);
96 printf("S11=%d S22=%d S12=%d\n", (int)S11, (int)S22, (int)S12);
97 printf("SYY=%d S1Y=%d S2Y=%d\n", (int)SYY, (int)S1Y, (int)S2Y);
98 #endif
99
100 M = (S11 * S22 - S12 * S12);
101 if (M == 0) {
102 /* error */
103 return -1;
104 }
105
106 A = (S1Y * S22 - S2Y * S12) * scale / M;
107 B = (S2Y * S11 - S1Y * S12) * scale / M;
108 C = Ya - (A * X1a + B * X2a) / scale;
109
110 #if 0
111 printf("A=%d B=%d C=%d\n", (int)A, (int)B, (int)C);
112 #endif
113 *a = A;
114 *b = B;
115 *c = C;
116
117 return (0);
118 }
119