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#include <stdio.h>
#include <math.h>
#include <arkode/arkode.h> /* prototypes for ARKODE fcts., consts. */
#include <nvector/nvector_serial.h> /* serial N_Vector types, fcts., macros */
#include <sunmatrix/sunmatrix_dense.h> /* access to dense SUNMatrix */
#include <sunlinsol/sunlinsol_dense.h> /* access to dense SUNLinearSolver */
#include <arkode/arkode_direct.h> /* access to ARKDls interface */
#include <sundials/sundials_types.h> /* definition of type realtype */
#include <sundials/sundials_math.h>
/* Check function return value...
opt == 0 means SUNDIALS function allocates memory so check if
returned NULL pointer
opt == 1 means SUNDIALS function returns a flag so check if
flag >= 0
opt == 2 means function allocates memory so check if returned
NULL pointer
*/
int check_flag(void *flagvalue, const char *funcname, int opt)
{
int *errflag;
/* Check if SUNDIALS function returned NULL pointer - no memory allocated */
if (opt == 0 && flagvalue == NULL) {
fprintf(stderr, "\nSUNDIALS_ERROR: %s() failed - returned NULL pointer\n\n",
funcname);
return 1; }
/* Check if flag < 0 */
else if (opt == 1) {
errflag = (int *) flagvalue;
if (*errflag < 0) {
fprintf(stderr, "\nSUNDIALS_ERROR: %s() failed with flag = %d\n\n",
funcname, *errflag);
return 1; }}
/* Check if function returned NULL pointer - no memory allocated */
else if (opt == 2 && flagvalue == NULL) {
fprintf(stderr, "\nMEMORY_ERROR: %s() failed - returned NULL pointer\n\n",
funcname);
return 1; }
return 0;
}
/* f routine to compute the ODE RHS function f(t,y). */
int f(realtype t, N_Vector y, N_Vector ydot, void *user_data)
{
realtype *rdata = (realtype *) user_data; /* cast user_data to realtype */
realtype lamda = rdata[0]; /* set shortcut for stiffness parameter */
realtype u = NV_Ith_S(y,0); /* access current solution value */
/* fill in the RHS function: "NV_Ith_S" accesses the 0th entry of ydot */
NV_Ith_S(ydot,0) = lamda*u + 1.0/(1.0+t*t) - lamda*atan(t);
return 0; /* return with success */
}
/* Jacobian routine to compute J(t,y) = df/dy. */
int Jac(realtype t, N_Vector y, N_Vector fy, SUNMatrix J,
void *user_data, N_Vector tmp1, N_Vector tmp2, N_Vector tmp3)
{
realtype *rdata = (realtype *) user_data; /* cast user_data to realtype */
realtype lamda = rdata[0]; /* set shortcut for stiffness parameter */
realtype *Jdata = SUNDenseMatrix_Data(J);
/* Fill in Jacobian of f: set the first entry of the data array to set the (0,0) entry */
Jdata[0] = lamda;
return 0; /* return with success */
}
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