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

        private double SmoothedNoise( double x, double y )
        {
            int		xInt = (int) x;
            int		yInt = (int) y;
            double	xFrac = x - xInt;
            double	yFrac = y - yInt;

            // get four noise values
            double	x0y0 = Noise( xInt, yInt );
            double	x1y0 = Noise( xInt + 1, yInt );
            double	x0y1 = Noise( xInt, yInt + 1 );
            double	x1y1 = Noise( xInt + 1, yInt + 1 );

            // x interpolation
            double	v1 = CosineInterpolate( x0y0, x1y0, xFrac );
            double	v2 = CosineInterpolate( x0y1, x1y1, xFrac );
            // y interpolation
            return CosineInterpolate( v1, v2, yFrac );
        }