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      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
     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