double BC_lin(double *f, int j, int N, double* x, int *BC){
double d1, d2;
if (j == N-1){ // approximate the end points linearly
d1 = d2dx2(f, N-3, N, x, BC);
d2 = d2dx2(f, N-2, N, x, BC);
return ((x[N-1] - x[N-2])/(x[N-3] - x[N-2])) * (d1 - d2) + d2;
} else if (j == 0){
d1 = d2dx2(f, 1, N, x, BC);
d2 = d2dx2(f, 2, N, x, BC);
return (x[0] - x[1])/(x[2] - x[1]) * (d2 - d1) + d1;
} else {
return 0;
}
}
/* R interface for d2dx2. Returns array of derivatives
*/
void d2dx2_R(double *f, int *N, double* x, int* BC, double* result){
int j;
for (j = 0; j < N[0]; j++){
result[j] = d2dx2(f, j, N[0], x, BC);
}
}
void recombine_level (int l)
{
int i, j, count, done;
/* sweep right */
count= 0;
done = 0;
for (i=N-1; i>0; i--) /* search for first relevant point */
{
if (sd[i+1] == l/2 && sd[i] == l)
{
/* Look for points to the right that need recombination */
count = 0;
while (sd[i-count]==l && fabs(dx*dx*d2dx2(Tm,i-count)/(sd[i-count]*sd[i-count]))<1e-6)
count++;
i -= count;
if (count>10) {
done = 1;
printf("count = %d, %d, %d\n", count, i, l);
}
}
}
if (done && 0)
{
output_state("state", 0);
exit(0);
}
}
