/* nag_mesh_dim2_gen_inc (d06aac) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.0, 2024.
*/
#include <math.h>
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer i1, i, itrace, k, nedge, nelt, nv, nvb, nvb1, nvb2, nvb3, nvmax,
reftk;
double coef, power, pi2, r, theta, x0, y0, theta_i;
/* Arrays */
char pmesh[2];
double *bspace = 0, *coor = 0;
Integer *conn = 0, *edge = 0;
/* Nag Types */
Nag_Boolean smooth;
NagError fail;
INIT_FAIL(fail);
exit_status = 0;
printf("nag_mesh_dim2_gen_inc (d06aac) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
/* Reading of the geometry sizes */
scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &nvb1,
&nvb2, &nvb3, &nvmax);
nvb = nvb1 + nvb2 + nvb3;
nedge = nvb;
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 (!(bspace = NAG_ALLOC(nvb, double)) ||
!(coor = NAG_ALLOC(2 * nvmax, double)) ||
!(conn = NAG_ALLOC(3 * (2 * nvmax - 1), 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 */
i1 = 0;
pi2 = 2.0 * X01AAC;
/* Outer circle */
theta = pi2 / ((double)nvb1);
r = 1.0;
x0 = 0.0;
y0 = 0.0;
theta_i = 0.0;
for (i = 0; i < nvb1; ++i) {
theta_i = theta_i + theta;
coor[i1] = x0 + r * cos(theta_i);
coor[i1 + 1] = y0 + r * sin(theta_i);
i1 = i1 + 2;
}
/* Larger inner circle */
theta = pi2 / ((double)nvb2);
r = 0.49;
x0 = -0.5;
y0 = 0.0;
theta_i = 0.0;
for (i = 0; i < nvb2; ++i) {
theta_i = theta_i + theta;
coor[i1] = x0 + r * cos(theta_i);
coor[i1 + 1] = y0 + r * sin(theta_i);
i1 = i1 + 2;
}
/* Smaller inner circle */
theta = pi2 / ((double)nvb3);
r = 0.15;
x0 = -0.5;
y0 = 0.65;
theta_i = 0.0;
for (i = 0; i < nvb3; ++i) {
theta_i = theta_i + theta;
coor[i1] = x0 + r * cos(theta_i);
coor[i1 + 1] = y0 + r * sin(theta_i);
i1 = i1 + 2;
}
/* Boundary edges */
i1 = 0;
for (i = 0; i < nedge; ++i) {
edge[i1] = i + 1;
edge[i1 + 1] = i + 2;
edge[i1 + 2] = 1;
i1 = i1 + 3;
}
/* Joins */
edge[3 * nvb1 - 2] = 1;
edge[3 * nvb1 + 3 * nvb2 - 2] = nvb1 + 1;
edge[3 * nvb - 2] = nvb1 + nvb2 + 1;
scanf(" ' %1s '%*[^\n]", pmesh);
/* Initialize mesh control parameters */
for (i = 0; i < nvb; ++i)
bspace[i] = 0.05;
smooth = Nag_TRUE;
itrace = 0;
coef = 0.75;
power = 0.25;
/* Call to the mesh generator */
/* nag_mesh_dim2_gen_inc (d06aac).
* Generates a two-dimensional mesh using a simple
* incremental method
*/
nag_mesh_dim2_gen_inc(nvb, nvmax, nedge, edge, &nv, &nelt, coor, conn, bspace,
smooth, coef, power, itrace, 0, &fail);
if (fail.code == NE_NOERROR) {
if (pmesh[0] == 'N') {
printf(" nv =%6" NAG_IFMT "\n", nv);
printf(" nelt =%6" NAG_IFMT "\n", nelt);
} else if (pmesh[0] == 'Y') {
/* Output the mesh to view it using the NAG Graphics Library */
printf(" %10" NAG_IFMT "%10" NAG_IFMT "\n", nv, nelt);
for (i = 0; i < nv; ++i)
printf(" %15.6e %15.6e\n", coor[2 * i], coor[2 * i + 1]);
reftk = 0;
for (k = 0; k < nelt; ++k) {
printf(" %10" NAG_IFMT "%10" NAG_IFMT "%10" NAG_IFMT "%10" NAG_IFMT
"\n",
conn[3 * k], conn[3 * k + 1], conn[3 * k + 2], reftk);
}
} else {
printf("Problem with the printing option Y or N\n");
exit_status = -1;
goto END;
}
} else {
printf("Error from nag_mesh_dim2_gen_inc (d06aac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
END:
NAG_FREE(bspace);
NAG_FREE(coor);
NAG_FREE(conn);
NAG_FREE(edge);
return exit_status;
}