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	trangetest.c - numtools - perform numerical operations on vectors and matrices …
	git clone git://src.adamsgaard.dk/numtools
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	---
	trangetest.c (2170B)
	---
	1 #include <stdio.h>
	2 #include <stdlib.h>
	3 #include <err.h>
	4 #include <limits.h>
	5 #include <string.h>
	6 #include <unistd.h>
	7
	8 #include "util.h"
	9
	10 #define VALUESTR "@VAL@"
	11
	12 static void
	13 usage(void)
	14 {
	15 errx(1, "usage: rangetest [-n maxiter] cmd min_val max_val\n"
	16 "where cmd must contain the string '" VALUESTR "'");
	17 }
	18
	19 static int
	20 launch(char cmd, char cmd0, double val)
	21 {
	22 char *c;
	23
	24 if ((c = strstr(cmd0, VALUESTR)) == NULL)
	25 errx(1, VALUESTR " not found in cmd");
	26 if (strlcpy(cmd, cmd0, PATH_MAX) >= PATH_MAX)
	27 err(1, "cmd too long");
	28 sprintf(cmd + (c - cmd0), "%.17g%s >/dev/null",
	29 val, c + strnlen(VALUESTR, sizeof(cmd)));
	30 if (system(cmd)) {
	31 fprintf(stderr, "%.17g\n", val);
	32 return 1;
	33 } else
	34 printf("%.17g\n", val);
	35
	36 return 0;
	37 }
	38
	39 static void
	40 binary_search(char cmd, char cmd0, double minv, double maxv, int maxit…
	41 {
	42 int minfail, maxfail, iter = 0;
	43 double val;
	44
	45 minfail = launch(cmd, cmd0, minv);
	46 maxfail = launch(cmd, cmd0, maxv);
	47 if (minfail && maxfail)
	48 errx(2, "both min_val and max_val runs errored");
	49 else if (!minfail && !maxfail)
	50 errx(3, "both min_val and max_val ran successfully");
	51
	52 while (minv <= maxv && iter < maxiter) {
	53 val = minv + 0.5 * (maxv - minv);
	54 if (launch(cmd, cmd0, val)) {
	55 if (maxfail) {
	56 maxv = val;
	57 maxfail = 1;
	58 } else {
	59 minv = val;
	60 }
	61 } else {
	62 if (maxfail) {
	63 minv = val;
	64 } else {
	65 maxv = val;
	66 maxfail = 0;
	67 }
	68 }
	69 iter++;
	70 }
	71 }
	72
	73 int
	74 main(int argc, char *argv[])
	75 {
	76 int ch, maxiter = 10;
	77 double minv, maxv;
	78 char cmd0[PATH_MAX] = "", cmd[PATH_MAX] = "";
	79 const char *errstr;
	80
	81 while ((ch = getopt(argc, argv, "N:")) != -1) {
	82 switch (ch) {
	83 case 'N':
	84 maxiter = strtonum(optarg, 0, INT_MAX, &errstr);
	85 if (errstr != NULL)
	86 errx(1, "bad maxiter value, %s: %s", err…
	87 break;
	88 default:
	89 usage();
	90 }
	91 }
	92 argc -= optind;
	93 argv += optind;
	94 if (argc == 3) {
	95 if (strlcpy(cmd0, argv[0], sizeof(cmd0)) >= sizeof(cmd0))
	96 err(1, "cmd too long");
	97 minv = atof(argv[1]);
	98 maxv = atof(argv[2]);
	99 if (minv >= maxv)
	100 errx(1, "min_val must be smaller than max_val");
	101 binary_search(cmd, cmd0, minv, maxv, maxiter);
	102 } else
	103 usage();
	104
	105 return 0;
	106 }