void hello(void);    /*и祇粆и穦ノ⊿把计ㄧ计hello() */
double mysqrt(double);   /*穦ノmysqrt()ㄧ计,把计琌double计 */
int main()         /* 祘Α秨﹍舘 */
{
    float x;
  hello();         /* give the user some message */
  printf("X=? ");
  scanf("%f", &x);
  while(x >=0 ) {
    printf(" SQRT(%f)=%7.3f\n", x, mysqrt(x) );
    printf("X=? "); scanf("%f", &x);
  } /* while */
  return 0;
} /**************祘Αゎ***********/
void hello()
{
    printf("This program will ask you to input a value, say X.");
    printf("Then it will find the square root of X.");
    printf("The above process will continue ...");
    printf("Negative value will cease the program.");
} /* hello() */
double mysqrt(double x)
{
    double myans;
    myans = -1;
    if(x < 0) printf(" can not process negative number\n");
    else {
       myans = 0;  /* we guess the root is zero */
       while(myans*myans < x)  myans++;  /* 瞦0, 1, 2,...び */
       if(myans*myans>x){
          myans =myans-1;   /*び, е搭奔 ; 糶Θmyans--*/
          while(myans*myans < x)  myans = myans+0.1;
       };
       if(myans*myans>x){
          myans-=0.1;   /* this means :   myans = myans -0.1 */
          while(myans*myans < x)  myans += 0.01;
       }
       if(myans*myans>x){
          myans -= 0.01;
          while(myans*myans < x)  myans += 0.001;
       }
       /* I think the precison is good enought now */
    } /*else*/
    return myans;  /**  return myans value as our answer */
} /* end of mysqrt*/
/************************************************************************
爹:
    硂祘Αいㄧ计mysqrt()┮―キよ璝獶碞穦び, 硂獶程暗猭!
    莱赣т程钡氮, ㄒ, ―2キよ, 程莱σ納 1.415*1.415 籔
    1.414*1.414 耕钡2, ゑ耕瞶!
************************************************************************/