I'm attempting to create a program to figure out Delta-V for my Kerbal Space Program game, and C++ (being run in the Eclipse IDE) seems to believe that my attempt to call the "log()" function is actually me referencing an uncreated function. I highly appreciate any help in the matter!
#include <iostream>
#include <cmath>
using namespace std;
int main() {
cout << "Hello. Welcome to the Kerbal Space Program Delta V Calculator. \n";
cout << " \n";
cout << "Note that each stage must use the same engine for this calculator.";
cout << "\n";
cout << "\nHow many stages make up your rocket? :";
int stageNumber;
cin >> stageNumber;
//cout << "Your rocket has " << stageNumber << " stages.\n";
cout << "\n\nStart from the bottom stage, please. ";
//ACTUAL DELTA V CALCULATIONS
for(int currentStage = 1; currentStage <= stageNumber; currentStage = currentStage + 1){
cout << "What is the total mass of this stage? :";
int totalMass;
cin >> totalMass;
cout << "What is the fuel mass of this stage? :";
int fuelMass;
cin >> fuelMass;
cout << "\n";
int dryMass;
dryMass = totalMass - fuelMass;
cout << "Your dry mass is" << dryMass << "\n";
cout << "\n";
cout << "Give the specific impulse of this stage's engine. \n";
int iSP;
cin >> iSP;
cout << "Here is the Delta V of your rocket.\n";
int deltaMass;
deltaMass = totalMass/dryMass;
int deltaV;
deltaV = iSP * log(deltaMass);
cout << deltaV;
exit(0);
}
}
I think for your calculations you want to use double (which I would prefer here) or float variables. Now all decimal places are truncated as you do integer division. Also your loop will not do more than one iteration, as exit(0); is called which terminates the whole program. Remove it and exit your main function with return 0;. Your error message happens because there is no log(int) in cmath. This would also resolved by using double. If you get linker errors append linker option -lm.