need help with c++ program

[froxy]

I need some help with a c++ program for my class, i can't figure out whats going on.

Input: from the user

Output: standard output AND file named "program3.txt"

Write a program that will calculate both roots of a quadratic equation. The program should ask the user to input a, b, and c and then write both roots to standard output (the screen) and a file named "program3.txt".

Your program should print the roots ordered from least to greatest.


If the quadratic equation has a negative discriminant your program should output "NO REAL ROOTS".


If the two roots are the same only report one root.


ax2 + bx + c = 0

Sample Input 	Sample Output
1, -3, -10 	-2, 5
3, 6, 3 	-1
2, -2, -12 	-2, 3
3, -2, 20 	NO REAL ROOTS

Here is so far what ive got

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    double a, b, c, d;
    double root1, root2, temp;
    
    //output
    
    cout << "enter a, b, c";
    cin >> a >> b >> c;
    
    //process
    
    d = pow(b,2) - 4 * a * c;
    if(d >= 0)
    {
          root1 = (-b + sqrt(d))/(2 * a);
          }
          if(d > 0)
          {
                 root2 = (-b + sqrt(d))/(2*a);
                 }
                                  if(root1 > root2)
                 {
                                temp = root1;
                                root1 = root2;
                                root2 = temp;
                                }

                                
                                // output
                                
                                if(d >= 0)
                                {
                                        cout << root1 << " ";
                                        }
                                        if(d > 0)
                                        {
                                               cout << root2 << " " <<endl;
                                        }
                                        if(d < 0)
                                        {
                                               cout <<"No Real Roots" << " ";
                                               }
                                               cin.get();
                                               cin.get();
                                               return 0;
                                               }

Can someone help me out with the sample output. i get the 2nd integer, but i dont get the first.

 

[OnceUponATimeInMexico]

Erm... i'm not that advanced in programming, but have studied quadratic formulas abit...

Tell me if i'm wrong, but you have worked out root one and root two as the same.

root1 = (-b + sqrt(d))/(2 * a);
root2 = (-b + sqrt(d))/(2*a);

doesn't one of them need to be a minus?

root2 = (-b - sqrt(d))/(2*a);

If not it's probably me just reading it wrong.

As for your output i'm not entirley sure... sure.

Ill have a try of making this my self, looks fun =]

 

[OnceUponATimeInMexico]

I know you want to do this your self, as most people do. But i found this if you want to try see where you have gone wrong. Or look for a few hints.

// Determine real and complex roots of a quadratic equation and check results
// ax^2 + bx + c = 0

#include <iostream>
#include <math.h>
#include <complex>
using namespace std;

int main(void)
{
float a, b, c, x1, x2, root;
complex<float> z;

cout << "Roots of quadratic equation, Enter a, b and c ? ";
cin >> a >> b >> c;

root = b * b - 4.0f * a * c; // b*b - 4ac
if (root >= 0.0f) // if +
{
root = sqrt(root); // real roots
x1 = (-b + root) / (2.0f * a);
x2 = (-b - root) / (2.0f * a);
cout << "Real roots " << x1 << " and " << x2 << endl;
cout << "Test " << a * x1 * x1 + b * x1 + c // check result
<< " and " << a * x2 * x2 + b * x2 + c << endl;
}
else
{ // complex roots
root = sqrt(-root) / (2.0f * a);
x1 = -b / (2.0f * a);
cout << "Complex roots " << x1 << " +- i " << root << endl;
z = complex<float>(x1, root);
cout << "Test " << a * z * z + b * z + c; // check result
z = complex<float>(x1, -root);
cout << " and " << a * z * z + b * z + c << endl;
}
system("pause");
return 0;
}

 

[super_]

yes because someone just learning simple algebra definitely understands how complex and imaginary numbers work.