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	tstddev.c - numtools - perform numerical operations on vectors and matrices in …
	git clone git://src.adamsgaard.dk/numtools
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	---
	tstddev.c (1582B)
	---
	1 #include <err.h>
	2 #include <stdio.h>
	3 #include <stdlib.h>
	4 #include <unistd.h>
	5 #include <math.h>
	6 #include <limits.h>
	7 #include <unistd.h>
	8
	9 #include "util.h"
	10
	11 static void
	12 usage(void)
	13 {
	14 errx(1, "usage: stddev [-d delimstr] [-n] [-p prec] [-u]");
	15 }
	16
	17 int
	18 main(int argc, char *argv[])
	19 {
	20 int ch, prec = 17, finalnl = 1;
	21 size_t i, j, nf = 0, nr = 0, correction = 1;
	22 double means = NULL, stdvals = NULL, **vals = NULL;
	23 const char *errstr;
	24 char *delimstr = "\t";
	25
	26 if (pledge("stdio", NULL) == -1)
	27 err(2, "pledge");
	28
	29 while ((ch = getopt(argc, argv, "d:np:u")) != -1) {
	30 switch (ch) {
	31 case 'd':
	32 delimstr = optarg;
	33 break;
	34 case 'n':
	35 finalnl = 0;
	36 break;
	37 case 'p':
	38 prec = strtonum(optarg, -10, INT_MAX, &errstr);
	39 if (errstr != NULL)
	40 errx(1, "bad precision value, %s: %s", e…
	41 break;
	42 case 'u':
	43 correction = 0;
	44 break;
	45 default:
	46 usage();
	47 }
	48 }
	49 /argc -= optind;/
	50 /argv += optind;/
	51
	52 nr = fscanmatrix(stdin, &vals, &nf);
	53
	54 if (!(means = calloc(nf, sizeof(double))) \|\|
	55 !(stdvals = calloc(nf, sizeof(double))))
	56 err(1, "calloc");
	57
	58 for (i = 0; i < nf; i++) {
	59 means[i] = 0.0;
	60 for (j = 0; j < nr; j++)
	61 means[i] += vals[j][i];
	62 means[i] /= (double)nr;
	63 }
	64
	65 for (i = 0; i < nf; i++) {
	66 stdvals[i] = 0.0;
	67 for (j = 0; j < nr; j++)
	68 stdvals[i] += pow(vals[j][i] - means[i], 2.0);
	69 stdvals[i] = sqrt(stdvals[i] / ((double)(nr - correction…
	70 }
	71
	72 printfarr(delimstr, prec, stdvals, nf);
	73 if (finalnl)
	74 putchar('\n');
	75
	76 free(means);
	77 free(stdvals);
	78 for (i = 0; i < nr; i++)
	79 free(vals[i]);
	80 free(vals);
	81
	82 return 0;
	83 }