Unexpected loss of precision when dividing doubles

Question

I have a function getSlope which takes as parameters 4 doubles and returns another double calculated using this given parameters in the following way:

double QSw         


        

Answer 1

The following code:

#include 
using namespace std;

double getSlope(double a, double b, double c, double d){
    double slope;
    slope=(d-b)/(c-a);
    return slope;
}

int main( ) {
    double s = getSlope(2.71156, -1.64161, 2.70413, -1.72219);
    cout << s << endl;
}

gives a result of 10.8452 with g++. How are you printing out the result in your code?