IsSquare( )

[Jeffrey Walton]

Hi All,

I was wondering if the following would be an improvement for testing if a 
number is a square (from Integer.cpp). It is a quick and dirty test. I ask 
because I want to perform a lot if tests using IsSquare() on quadrtic residues.

bool Integer::IsSquare() const
{
    Integer r;
    word digit = 0;

    if( false == IsNegative( ) ) {
        Integer::Divide(digit, r, *this, 10);

        //\ Perfect squares end in the following
        if( digit != 0 && digit != 1 && digit != 4 &&
            digit != 5 && digit != 6 && digit != 9 ) { return false; }
    }

    r = SquareRoot();
    return *this == r.Squared();
}