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#include "header.h"
#include <iomanip>
using namespace std;
int main(void)
{
char Reply;
coetype header;
do
{
cout << "Quadratic Equation Solver" << endl << endl;
input(header);
solution(header);
PrintSolutions(header);
cout << "Solve another (y/n)? ";
cin >> Reply;
}
while (Reply == 'y');
}
// Given: Nothing
// Task: Ask the user for the values for the coefficients a, b, and c.
// Return: a, b, and c.
void input(coetype & header)
{
cout << "Enter the value of coefficient a: ";
cin >> header.a;
cout << "Enter the value of coefficient b: ";
cin >> header.b;
cout << "Enter the value of coefficient c: ";
cin >> header.c;
}
// Given: The coefficients a, b, c of the quadratic equation
// Task: Normalize a, b, c.
// Return: return a, b, c in their normalized form.
void normalize(coetype & header)
{
float Largest;
if (fabs(header.a) > fabs(header.b))
Largest = fabs(header.a);
else
Largest = fabs(header.b);
if (fabs(header.c) > Largest)
Largest = fabs(header.c);
header.a = header.a / Largest;
header.b = header.b / Largest;
header.c = header.c / Largest;
}
// Given: a, b, c The coefficients of a quadratic equation.
// Task: Calculates the discriminant for the quadratic equation with these coefficients.
// Return: This discriminant is returned in the function name.
float Discriminant(coetype & header)
{
return pow(header.b, 2) - 4.0f * header.a * header.c;
}
// Given: a, b, c, the coefficients of a quadratic equation.
// Task: Is to use a, b, and c to find the real solutions.
// Return: x1 and x2, the solutions, where x1 and x2 are both valid when NumSolutions is 1,
// only x1 is valid if NumSolutions is 1, and neither is valid if NumSolutions is 0.
// NumSolutions: the number of real solutions to the quadratic equation.
void solution(coetype & header)
{
float Root;
normalize(header);
header.discrim = Discriminant(header);
if (header.discrim < 0)
header.NumSolutions = 0;
else if (header.discrim == 0)
{
header.x1 = -header.b / (2.0f * header.a);
header.NumSolutions = 1;
}
else // Discriminant must be positive
{
Root = sqrt(header.discrim);
header.NumSolutions = 2;
if (-header.b > 0)
header.x1 = (-header.b + Root) / (2.0f * header.a);
else
header.x1 = (-header.b- Root) / (2.0f * header.a);
header.x2 = header.c / (header.a * header.x1);
}
}
// Given: NumSolutions for the number of solutions that we have,
// we are also given our answers x1, and x2 (where x1 and x2 are valid as in
// the previous function.)
// Task: Is to print the answers of the quadratic equation to the screen.
// Return: Nothing.
void PrintSolutions(coetype & header)
{
if (header.NumSolutions == 0)
cout << "No real solutions" << endl;
else if (header.NumSolutions == 1)
cout << "One real solution: " << "x1:" << header.x1 << endl;
else
cout << "Two real solutions: " << "x1:" << header.x1 << " and " << "x2:" << header.x2 << endl;
}
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