algorithm - How to solve some algebraic expressions and find the GCD of a number and one obtained from evaluating the algebra in Java -

i'm writing java program find gcd (greatest common divisor) of number n. program should evaluate algebraic expression. lemme explain further; 1. calculate √(n) 2. divide result of (1) above 18. 3. compute ceiling function of step(2) above , call f. in other words, f = ceiling function of [√(n) divided 18]. 4. set following 3 algebraic expressions in x , execute them sequentially (a) (c):

a) h1(x) = (n -1-18x ), x take values 0 f. each x, compute gcd of h1(x) , n. let’s call gcd, d. is, d= gcd (n, h1(x)) or ( n, h1(x)). if d =1, increase x 1 , continue until d > 1 or come x = f. if d > 1, have found 1 nontrivial divisor of n. call q. other divisor of n value of h1(x) divided q plus 1. let’s call p. therefore, p = ( +1). state divisors of n p , q. prompt n entered or ask if user wants enter n tested- y/n option.

but if not find gcd > 1 h1(x) between x = 0 , x = f, move (b) below:

b) h2(x) = (n -11-18x ), x range 0 f. each x, compute gcd of h2(x) , n. let’s call gcd, d. is, d= gcd(n, h2(x)) or ( n, h2(x)). if d =1, increase x 1 , continue until d > 1 or come x = f.

if d > 1, have found 1 nontrivial divisor of n. call q. other divisor of n value of h2(x) divided q. let’s call p.

therefore, p = ( +1). state divisors of n p , q. prompt n entered or ask if user wants enter n tested- y/n option.

but if not find gcd > 1 h2(x) between x = 0 , x = f, move (c) below:

c) h4(x) = (n -13-18x ), x range 0 f. each x, compute gcd of h4(x) , n. let’s call gcd, d. if d =1, increase x 1 , continue until d > 1 or come x = f. if d > 1, have found 1 nontrivial divisor of n. call q. other divisor of n value of h4(x) divided q. let’s call p.

therefore, p = ( +1).

then state divisors of n p , q.

see i've done far;

public static void main(string[] args) {      int num;     double sqrtnum;     double dividedsqrtnum;     double f;     int x = 0;     float a;     int d;     float p;     int q;       scanner input = new scanner(system.in);        system.out.println("enter number 'n'");      num = input.nextint();       if( (num % 3) != 0){           system.out.println( "the number entered semi-prime");           sqrtnum = math.sqrt(num);           dividedsqrtnum = sqrtnum / 18;           f = math.ceil(dividedsqrtnum) ;           system.out.println("the value of f " + f);           // algebraic expressions           (x=0; x <= f; x++){               while (d == 1 || x ==f){           = (num - 1 - 18 * x);     d = findgcd(num,a);         if ( d == 1){          x = x++;         }          else{             q = d;             p = (a / q + 1);              system.out.println("the divisors of "+ num +" "+ p +" , " + q +" want test number? y or n " );             }                      }                                 }                             }       else{          system.out.println("the number not semi-prime");       } 

}

 private static int findgcd(float num,float a) {         //base case          return findgcd(a, num%a);     }  } 

help me guys, i'm stuck.