double* squares_copy(double a[],
                     unsigned int alen) {
    double* res = (double*)malloc(sizeof(double) * alen);
    if (res == NULL) {
        fprintf(stderr, "squares_copy: unable to allocate result array\n");
        exit(1);
    }
    unsigned int i;

    for (i = 0; i < alen; i++) {
        res[i] = a[i] * a[i];
    }

    return res;
}

void baz() {
    double xs[] = {1, 2, 3};
    double* ys = squares_copy(xs, 3);
    // ... use ys ...
    free(ys);
}