long double complex *v; v = (long double complex *)malloc(sizeof(long double complex) * N);

long double complex *y; y = (long double complex *)malloc(sizeof(long double complex) * N);

long double complex w;

int k;

for (k = 0; k < N; k++) {
    y[k] = 0;
    v[k] = 0;
}
w = a[0];
y[0] = f[0] / w;
for (k = 1; k < N; k++) {
    v[k - 1] = c[k - 1] / w;
    w = a[k] - b[k] * v[k - 1];
    y[k] = (f[k] - b[k] * y[k - 1]) / w;
}
for (k = N - 2; k >= 0; k--) {
    y[k] = y[k] - v[k] * y[k + 1];
}
return y;