Answer 1

#include <iostream>
#include <iomanip>
using namespace std;

//with this function we can calculate the factorial of a number n
float factorial(int n) {
if ((n==1)||(n==0)) {
return 1;
}
else {
return n * factorial(n-1);
}
}

//after this summation we should find the value of e
void numbere(int i, double& e) {
for (int j=0;j<=i;j++) {
e+=1.0/factorial(j);
}

}

//prints e
int main() {
double e=0;
numbere(10,e);
cout<<"The number e is equal to "<<e<<endl;
return 0;
}

Answer 2

In main() you call numbere() without parameters;

try:

cout << "The number e is equal to "<< numbere(10) << endl;

Answer 3

Another thing is you return before the loop ends in numbere(), so the value returned is wrong.

Answer 4

Anyway you should use a reference to e (&) in numbere() since you want to modify it.

Answer 5

The reason why it gives a wrong value is that you start the series at i=1 instead of 0. have fixed it now. See editing of previous code.

Answer 6

@Frederico, yes I have noticed this. It does not work for long doubles apparently but works for floats or doubles.

Answer 7

Your code gives me ~1.718 if I change e to a double type . Which is not correct. You will have to review your algorithm. ;)

Answer 8

You are missing parenthesis

return ( e+= ( 1.0 / factorial (i) ) );

Assingment evaluates before any calculus