AForge.Math.PerlinNoise.Noise C# (CSharp) Method

        private double Noise( int x, int y )
        {
            int n = x + y * 57;
            n = ( n << 13 ) ^ n;

            return ( 1.0 - ( ( n * ( n * n * 15731 + 789221 ) + 1376312589 ) & 0x7fffffff ) / 1073741824.0 );
        }