```/* nag_mesh2d_delaunay (d06abc) Example Program.
*
* NAGPRODCODE Version.
*
* Copyright 2016 Numerical Algorithms Group.
*
* Mark 26, 2016.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagd06.h>

#define EDGE(I, J) edge[3*((J) -1)+(I) -1]
#define CONN(I, J) conn[3*((J) -1)+(I) -1]
#define COOR(I, J) coor[2*((J) -1)+(I) -1]

int main(void)
{
const Integer nvmax = 6000, nvint = 40;
double dnvint;
Integer exit_status, i, itrace, j, k, nedge, nelt,
npropa, nv, nvb, reftk, i1, nearest, nv_near, nelt_near;
NagError fail;
char pmesh[2];
double *coor = 0, *weight = 0;
Integer *conn = 0, *edge = 0;

INIT_FAIL(fail);

exit_status = 0;

printf("nag_mesh2d_delaunay (d06abc) Example Program Results\n\n");

/* Skip heading in data file */
scanf("%*[^\n] ");

/* Reading of the geometry */
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &nvb, &nedge);

if (nvb > nvmax) {
printf("Problem with the array dimensions\n");
printf(" nvb nvmax %6" NAG_IFMT "%6" NAG_IFMT "\n", nvb, nvmax);
printf(" Please increase the value of nvmax\n");
exit_status = -1;
goto END;
}

/* Allocate memory */

if (!(coor = NAG_ALLOC(2 * nvmax, double)) ||
!(weight = NAG_ALLOC(nvint, double)) ||
!(conn = NAG_ALLOC(3 * (2 * nvmax + 5), Integer)) ||
!(edge = NAG_ALLOC(3 * nedge, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Coordinates of the boundary mesh vertices and boundary edges */

for (i = 1; i <= nvb; ++i) {
scanf("%" NAG_IFMT "", &i1);
scanf("%lf", &COOR(1, i1));
scanf("%lf", &COOR(2, i1));
scanf("%*[^\n] ");
}

for (i = 1; i <= nedge; ++i) {
scanf("%" NAG_IFMT "", &i1);
scanf("%" NAG_IFMT "", &EDGE(1, i1));
scanf("%" NAG_IFMT "", &EDGE(2, i1));
scanf("%" NAG_IFMT "", &EDGE(3, i1));
scanf("%*[^\n] ");
}
scanf(" ' %1s '%*[^\n]", pmesh);

/* Initialize mesh control parameters */

itrace = 0;

/* Generation of interior vertices on the RAE airfoils wake */

dnvint = 2.5 / (double) (nvint + 1);

for (i = 1; i <= nvint; ++i) {
i1 = nvb + i;
COOR(1, i1) = (double) i *dnvint + 1.38;
COOR(2, i1) = -0.27 * COOR(1, i1) + 0.2;
weight[i - 1] = 0.01;
}

/* Loop on the propagation coef */

nearest = 250;
for (j = 0; j < 4; ++j) {
switch (j) {
case 0:
npropa = -5;
break;
case 1:
npropa = -1;
break;
case 2:
npropa = 1;
break;
default:
npropa = 5;
}

/* Call to the 2D Delaunay-Voronoi mesh generator */

/* nag_mesh2d_delaunay (d06abc).
* Generates a two-dimensional mesh using a Delaunay-Voronoi
* process
*/
nag_mesh2d_delaunay(nvb, nvint, nvmax, nedge, edge, &nv, &nelt, coor,
conn, weight, npropa, itrace, 0, &fail);

if (fail.code == NE_NOERROR) {
if (pmesh[0] == 'N') {
printf(" Mesh characteristics with npropa =%6" NAG_IFMT "\n", npropa);
nv_near = ((nv+nearest/2)/nearest)*nearest;
nelt_near = ((nelt+nearest/2)/nearest)*nearest;
printf(" nv   =%10" NAG_IFMT " to the nearest %3" NAG_IFMT "\n",
nv_near, nearest);
printf(" nelt =%10" NAG_IFMT " to the nearest %3" NAG_IFMT "\n",
nelt_near, nearest);
}
else if (pmesh[0] == 'Y') {
/* Output the mesh in a form suitable for printing */

printf(" %10" NAG_IFMT " %10" NAG_IFMT "\n", nv, nelt);

for (i = 1; i <= nv; ++i) {
printf("  %15.6e  %15.6e  \n", COOR(1, i), COOR(2, i));
}

reftk = 0;
for (k = 1; k <= nelt; ++k) {
printf(" %10" NAG_IFMT " %10" NAG_IFMT " %10" NAG_IFMT ""
" %10" NAG_IFMT "\n", CONN(1, k), CONN(2, k),
CONN(3, k), reftk);
}
}
else {
printf("Problem with the printing option Y or N\n");
exit_status = -1;
goto END;
}
}
else {
printf("Error from nag_mesh2d_delaunay (d06abc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
}

END:
NAG_FREE(coor);
NAG_FREE(weight);
NAG_FREE(conn);
NAG_FREE(edge);

return exit_status;
}
```