```/* nag_quad_md_simplex (d01pac) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 23, 2011.
*/

#include <stdio.h>
#include <math.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagd01.h>

#ifdef __cplusplus
extern "C" {
#endif
static double NAG_CALL functn(Integer ndim, const double x[], Nag_Comm *comm);
#ifdef __cplusplus
}
#endif

int main(void)
{
#define VERT(I, J) vert[(J-1)* (ndim+1) + I-1]
/* Scalars */
Integer  exit_status = 0;
Integer  i, j, maxord, minord, mxord, ndim;
double   esterr;
/* Arrays */
Integer  iuser[1];
double   *finvls = 0, *vert = 0;
/* Nag types */
NagError fail;
Nag_Comm comm;

INIT_FAIL(fail);

printf("nag_quad_md_simplex (d01pac) Example Program Results\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
/* Input mxord and ndim */
scanf("%ld %ld%*[^\n] ", &mxord, &ndim);

if (!(finvls = NAG_ALLOC(mxord, double)) ||
!(vert = NAG_ALLOC(2*(ndim+1)*(ndim+1), double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

for (i = 1; i <= ndim+1; i++)
for (j = 1; j <= ndim; j++) VERT(i, j) = 0.0;
for (j = 2; j <= ndim+1; j++) VERT(j, j - 1) = 1.0;

minord = 0;
iuser[0] = 0; /* Function counter */
comm.iuser = iuser;
for (maxord = 1; maxord <= mxord; maxord++)
{
/* nag_quad_md_simplex (d01pac).
* Multidimensional quadrature over an n-simplex.
*/
nag_quad_md_simplex(ndim, vert, functn, &minord, maxord, finvls,
&esterr, &comm, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_quad_md_simplex (d01pac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

if (maxord == 1)
printf("maxord   Estimated      Estimated         Integrand\n"
"           value         accuracy        evaluations\n");
printf("%4ld%13.5f%16.3e%15ld\n",
maxord, finvls[maxord-1], esterr, comm.iuser[0]);
}

END:
NAG_FREE(finvls);
NAG_FREE(vert);

return exit_status;
}

static double  NAG_CALL functn(Integer ndim, const double x[], Nag_Comm *comm)
{
comm->iuser[0]++;
return exp(x[0] + x[1] + x[2]) * cos(x[0] + x[1] + x[2]);
}
```