#include <iostream>
#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagd02.h>
#include <nagx01.h>
#ifdef __cplusplus
extern "C" {
#endif
static void NAG_CALL fcn(Integer neq, double x, double eps, const double y[],
double f[], Nag_User *comm);
static void NAG_CALL g(Integer neq, double eps, const double ya[],
const double yb[], double bc[], Nag_User *comm);
#ifdef __cplusplus
}
#endif
#define NEQ 2
#define MNP 40
#define Y(I, J) y[(I) *tdy + J]

int main()
{
    static Integer use_comm[6] = {1, 1, 1, 1, 1, 1};
    double *abt = 0;
    double deleps;
    double tol;
    double *x = 0, *y = 0;
    Integer exit_status = 0;
    Integer i, j;
    Integer np;
    Integer numbeg, nummix;
    Integer neq, mnp, tdy;
    Nag_User comm;
    NagError fail;
    INIT_FAIL(fail);
    comm.p = (Pointer)&use_comm;
    neq = NEQ;
    mnp = MNP;
    if (neq >= 1)
    {
    if (!(abt = NAG_ALLOC(neq, double)) ||
    !(x = NAG_ALLOC(mnp, double)) ||
    !(y = NAG_ALLOC(neq*mnp, double)))
    {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
    }
    tdy = mnp;
    }
    else
    {
    exit_status = 1;
    return exit_status;
    }
    tol = 1.0e-4;
    np = 17;
    numbeg = 1;
    nummix = 0;
    x[0] = 0.0;
    x[np-1] = nag_pi;
    deleps = 0.1;
    nag_ode_bvp_fd_nonlin_gen(neq, &deleps, fcn, numbeg, nummix, g,
    Nag_DefInitMesh, mnp, &np, x, y, tol, abt, NULLFN,
    NULLFN, NULLFN, NULLFN, &comm, &fail);
    if (fail.code != NE_NOERROR)
    {
    printf("Error from nag_ode_bvp_fd_nonlin_gen (d02rac).\n%s\n",
    fail.message);
    exit_status = 1;
    goto END;
    }
    printf("Solution on final mesh of %"" points \n", np);
    printf(" X Y(1) Y(2) Y(3)\n");
    for (j = 0; j < np; ++j)
    {
    printf(" %9.3f ", x[j]);
    for (i = 0; i < neq; ++i)
    printf(" %9.4f", Y(i, j));
    printf("\n");
    }
    printf("\n\nMaximum estimated error by components \n");
    for (i = 1; i <= 3; ++i)
    printf(" %11.2e", abt[i-1]);
    printf(" \n");
    END:
    NAG_FREE(abt);
    NAG_FREE(x);
    NAG_FREE(y);
    return exit_status;
}
static void NAG_CALL fcn(Integer neq, double x, double eps, const double y[],
double f[], Nag_User *comm)
{
Integer *use_comm = (Integer *)comm->p;
if (use_comm[0])
{
printf("(User-supplied callback fcn, first invocation.)\n");
use_comm[0] = 0;
}
f[0] = -y[1];
f[1] = y[0];
}

static void NAG_CALL g(Integer neq, double eps, const double ya[],
const double yb[], double bc[], Nag_User *comm)
{
Integer *use_comm = (Integer *)comm->p;
if (use_comm[1])
{
printf("(User-supplied callback g, first invocation.)\n");
use_comm[1] = 0;
}
bc[0] = yb[0]-0;
bc[1] = ya[1]-1;
}