#include <stdio.h>
#include <math.h>
#define FIO "written by\nManakina Alyona"
#define gr "student group 833"
#define lr7 "Laboratory work 7"
#define stars printf("\n****************")
void representation()                                                           // Student presentation function
    {
        stars;
        printf("\n%s\n%s\n%s", lr7, gr, FIO);
        stars;

    }


void get_roots( double a, double b, double c)   // The function to calculate the roots of the equation,
    double x1,x2,d;
{
   if (a == 0)                                                                  // where a,b,c are input parameters, and x1,x2 are roots, d is discriminant
    {
        if (b == 0 )
        printf (" \n No roots");                                                // Result output
        else

         x1 = - c/b;                                                            // Root calculation formula
         printf ("\n One root x1 = %lf", x1);                                   // Result output

    }
    else
        d=b*b-4*a*c;                                                            // Discriminant calculation formula
        if (d>0)
            {
                x1=(sqrt(d)-b)/(2*a);                                           // Roots calculation formulas
                x2=(-sqrt(d)-b)/(2*a);
                printf("\nRoots of the equation \nx1 = %lf,\nx2 = %lf", x1,x2); // Result output

            }
        else
            if (d<0)
                printf("\n No roots");                                          // Result output
            else
                if (d==0)
                {
                    x1=-b/(2*a);                                                // Root calculation formula
                    printf("\n One root x1= %lf", x1);                          // Result output

                }

} //get_roots(a, b, c, x1, x2, d)
void main()                                                                     // Main function
{
    double a;                                                                   // Senior equation coefficient
    double b;                                                                   // Сoefficient
    double c;                                                                   // Free member
    double d;                                                                   // Discriminant
    double x1, x2;                                                              // Roots

    representation();                                                           // Call function representation()

    printf("\nEnter a: ");                                                      // Input
    scanf("%lf", &a);
    printf("\nEnter b: ");                                                      // Input
    scanf("%lf", &b);
    printf("\nEnter c: ");                                                      // Input
    scanf("%lf", &c);

    get_roots(a, b, c);                                              // Call function  get_roots(a, b, c, x1, x2, d)

} // main()