#include <stdio.h>
#include <math.h>
#include <stdlib.h>

/* 10 million */
#define N 10000000

/* the kernel fills an array up with square roots */
void square_roots(double* array) {
    unsigned int i;
    for (i = 0; i < N; i++) {
        array[i] = sqrt((double) i);
    }
}

int main() {
    /* store the square roots of 0 to (N-1) on the CPU
     * stored on the heap since it's too big for the stack for large values of N */
    double* roots = (double*) malloc(N * sizeof(double));

    /* calculate the square roots on the CPU */
    square_roots(roots);

    /* print out 100 evenly spaced square roots just to see that it worked */
    unsigned int i;
    for (i = 0; i < N; i += (N / 100)) {
        printf("sqrt(%d) = %lf\n", i, roots[i]);
    }

    /* free the CPU memory */
    free(roots);

    return 0;
}