NAG Library Manual, Mark 30.1
/* nag_nonpar_test_chisq (g08cgc) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.1, 2024.
*
*
*/

#include <nag.h>
#include <stdio.h>

int main(void) {
/* Integer scalar and array declarations */
Integer exit_status = 0, i, n, nclass, ndf, npest, lstate;
Integer *ifreq = 0, *state = 0;

/* NAG structures */
Nag_ClassBoundary classb;
Nag_Distributions cdist;
NagError fail;

/* Double scalar and array declarations */
double chisq, *chisqi = 0, *cint = 0, *eval = 0, p, *par = 0;
double *prob = 0, *x = 0, xmax, xmin;

/* Character array declarations */
char nag_enum_arg[40];

/* Choose the base generator */
Nag_BaseRNG genid = Nag_Basic;
Integer subid = 0;

/* Set the seed */
Integer seed[] = {1762543};
Integer lseed = 1;

INIT_FAIL(fail);

printf("nag_nonpar_test_chisq (g08cgc) Example Program Results\n");

/* Get the length of the state array */
lstate = -1;
nag_rand_init_repeat(genid, subid, seed, lseed, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_repeat (g05kfc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT " %" NAG_IFMT "  %39s %*[^\n] ", &n, &nclass,
nag_enum_arg);

/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
cdist = (Nag_Distributions)nag_enum_name_to_value(nag_enum_arg);

if (!(x = NAG_ALLOC(n, double)) || !(state = NAG_ALLOC(lstate, Integer)) ||
!(cint = NAG_ALLOC(nclass - 1, double)) ||
!(par = NAG_ALLOC(2, double)) || !(ifreq = NAG_ALLOC(nclass, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

for (i = 1; i <= 2; ++i)
scanf("%lf", &par[i - 1]);
npest = 0;

/* Initialize the generator to a repeatable sequence */
nag_rand_init_repeat(genid, subid, seed, lseed, state, &lstate, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_init_repeat (g05kfc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Generate random numbers from a uniform distribution */
nag_rand_dist_uniform(n, par[0], par[1], state, x, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_rand_dist_uniform (g05sqc).\n%s\n", fail.message);
return 1;
}

classb = Nag_ClassBoundaryComp;
/* Determine suitable intervals */
if (cdist == Nag_Uniform) {
classb = Nag_ClassBoundaryUser;
cint[0] = par[0] + (par[1] - par[0]) / nclass;
for (i = 2; i <= nclass - 1; ++i)
cint[i - 1] = cint[i - 2] + (par[1] - par[0]) / nclass;
}

/* nag_stat_frequency_table (g01aec).
* Frequency table from raw data
*/
nag_stat_frequency_table(n, x, nclass, classb, cint, ifreq, &xmin, &xmax,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_stat_frequency_table (g01aec).\n%s\n", fail.message);
return 1;
}

if (!(chisqi = NAG_ALLOC(nclass, double)) ||
!(eval = NAG_ALLOC(nclass, double)) ||
!(prob = NAG_ALLOC(nclass, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
/* nag_nonpar_test_chisq (g08cgc).
* Performs the chi^2 goodness of fit test, for standard
* continuous distributions
*/
nag_nonpar_test_chisq(nclass, ifreq, cint, cdist, par, npest, prob, &chisq,
&p, &ndf, eval, chisqi, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_nonpar_test_chisq (g08cgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
printf("\n");
printf("%s%10.4f\n", "Chi-squared test statistic   = ", chisq);
printf("%s%5" NAG_IFMT "\n", "Degrees of freedom.          = ", ndf);
printf("%s%10.4f\n", "Significance level           = ", p);
printf("\n");
printf("%s\n", "The contributions to the test statistic are :-");
for (i = 1; i <= nclass; ++i)
printf("%10.4f\n", chisqi[i - 1]);
END:
NAG_FREE(x);
NAG_FREE(cint);
NAG_FREE(par);
NAG_FREE(ifreq);
NAG_FREE(chisqi);
NAG_FREE(eval);
NAG_FREE(prob);
NAG_FREE(state);
return exit_status;
}