math-exp-cpp

float_data.py

import struct
import math


def bytes_to_double(data):
    return struct.unpack('d', data)[0]

def double_to_bytes(data):
    return struct.pack('d', data)

def bytes_to_hex_string(data):
    return ' '.join('{:02x}'.format(x) for x in data)

inputBytes = bytes([14, 243, 143, 0, 124, 41, 85, 64])
inputD = bytes_to_double(inputBytes)

print(bytes_to_hex_string(inputBytes))
print(inputD)
outputD = math.exp(inputD)
outputBytes = double_to_bytes(outputD)

print(bytes_to_hex_string(outputBytes))
print(outputD)

math_exp.cpp

#include <iostream>
#include <sstream>
#include <iomanip>
#include <math.h> 
#include <string>

using namespace std;

typedef unsigned char uchar;

string doubleToHexString(double d){
    uchar * bytes = (uchar*) &d;
    stringstream out;
    for (int i = 0; i < 8; ++i){
        out << hex << setfill('0') << setw(2) << (int) bytes[i] << " ";
    }
    return out.str();
}

int main() {
    unsigned char input[] = {14, 243, 143, 0, 124, 41, 85, 64 };

    double* inputD = (double*)input;
    double outputD = exp(*inputD);
    cout<<"exp(" << *inputD << "\thex: " << doubleToHexString(*inputD) <<"\t=\t" \
    <<outputD<<"\thex: "<<doubleToHexString(outputD)<<" ) "<<endl;

    outputD = sqrt(*inputD);
    cout<<"sqrt(" << *inputD << "\thex: " << doubleToHexString(*inputD) <<"\t=\t" \
    <<outputD<<"\thex: "<<doubleToHexString(outputD)<<" ) "<<endl;

    outputD = *inputD * *inputD;
    cout<<"mul(" << *inputD << "\thex: " << doubleToHexString(*inputD) <<"\t=\t" \
    <<outputD<<"\thex: "<<doubleToHexString(outputD)<<" ) "<<endl;

}
// windows 7, mingw-64 g++: 
// exp(84.6482     hex: 0e f3 8f 00 7c 29 55 40 )  =       5.7842e+36      hex: 9a 64 2e 68 fc 67 91 47  )

// Apple LLVM version 8.0.0 (clang-800.0.42.1):
// exp(84.6482 hex: 0e f3 8f 00 7c 29 55 40    =   5.7842e+36  hex: 99 64 2e 68 fc 67 91 47  )


// g++-7 (Homebrew GCC 7.2.0) 7.2.0:
// exp(84.6482  hex: 0e f3 8f 00 7c 29 55 40    =   5.7842e+36  hex: 99 64 2e 68 fc 67 91 47  )

// windows-server, mingw-64 g++: 
// exp(84.6482     hex: 0e f3 8f 00 7c 29 55 40 )  =       5.7842e+36      hex: 9a 64 2e 68 fc 67 91 47  )

// windows-server, mingw-32 g++: 
// exp(84.6482     hex: 0e f3 8f 00 7c 29 55 40 )  =       5.7842e+36      hex: 99 64 2e 68 fc 67 91 47  )