Serial to parallel convert

static void calc(const double b[120], const double x[163970], double y[163970])
{
	int k, j;
	memset(&y[0], 0, 163970U * sizeof(double));
	for (k = 0; k < 120; k++) {
		for (j = k; j + 1 < 163971; j++) {
			y[j] += b[k] * x[j - k];
		}
	}
}