#include <stdio.h>
#include <stdint.h>
#include <string.h>

int main()
{
    uint64_t vbi = 0x4141414142424242ULL; // hex representation of double
    double r, vb, va = 1.4426950408889634074;

    memcpy(&vb, &vbi, sizeof(vb));        // copy hex to double
    r = va * vb;
    printf("va = %f, vb = %f, r = %f\n", va, vb, r);
    return 0;
}