gaussian1D

	// 1D gaussian kernel
	//	pretty much ripped from here: http://www.apileofgrains.nl/blur-filters-c/
	vector<float> gaussianKernel( int radius, float weight = 1.)
	{
		int mem_amount = (radius*2)+1;
		vector<float> kernel( (radius*2) + 1 );
		
		float twoRadiusSquaredRecip = 1.0 / (2.0 * radius * radius);
		float sqrtTwoPiTimesRadiusRecip = 1.0 / (sqrt(2.0 * PI) * radius);
		
		// Create Gaussian Kernel
		int r = -radius;
		float sum = 0, x, v;
		for (int i = 0; i < kernel.size(); i++)
		{
			v = sqrtTwoPiTimesRadiusRecip * exp(-pow(r * weight, 2) * twoRadiusSquaredRecip);
			kernel[i] = v;
			
			sum+=v;
			r++;
		}
		
		// normalize
		for (auto& k: kernel)	k /= sum;
		
		return kernel;
	}