Check if BigInteger is not a perfect square

Question

I have a BigInteger value, let\'s say it is 282 and is inside the variable x. I now want to write a while loop that states:

while b2 isn\'t a perfect square:         


        

Answer 1

using System.Numerics; // needed for BigInteger

/* Variables */
BigInteger a, b, b2, n, p, q;
int flag;

/* Assign Data */
n = 10147;
a = iSqrt(n);

/* Algorithm */
do
{   a = a + 1;
    b2 = (a * a) – n;
    b = iSqrt(b2);
    flag = BigInteger.Compare(b * b, b2);
} while(flag != 0);

/* Output Data */
p = a + b;
q = a – b;


/* Method */
    private static BigInteger iSqrt(BigInteger num)
    { // Finds the integer square root of a positive number            
        if (0 == num) { return 0; }     // Avoid zero divide            
        BigInteger n = (num / 2) + 1;   // Initial estimate, never low            
        BigInteger n1 = (n + (num / n)) / 2;
        while (n1 < n)
        {   n = n1;
            n1 = (n + (num / n)) / 2;
        }
        return n;
    } // end iSqrt()