equroot.c

自己做的常用库和实现的数据结构。public domain.

/*
  Ex5_4
  Find the result of ax^2+bx+c=0
*/

/* abs */
#define abs(x) ((x<0)?-(x):x)
#define acc 0.000001

float sqrt(x)
float x;
{
    float guess = 1;

    while (abs(guess*guess-x) >= acc)
        guess = (x/guess + guess)/2;
    return(guess);
}

float a,b,c;
void confficients()
{
    printf ("input a,b,c!\n");
    scanf ("%f %f %f",&a,&b,&c);
}

main()
{
    float chcker;

    confficients();
    chcker = b * b - 4 * a * c;
    if (chcker < 0)
        printf ("no virtual roots\n");
    else
        printf ("root1=%f\nroot2=%f\n",
			  (sqrt(chcker)-b)/2/a,
			 - (sqrt(chcker)+b)/2/a);
}