I am trying to apply a Gaussian decay value to a set of distances measured in meters using the field calculator in QGIS.
My distances range from circa 50 to 12,000 meters. I am using the following equation which works but I am confused by the sigma value. Mainly it's purpose and how you find a suitable value for your data set so it is meaningful. For my range I need a sigma value into the 1000s before a number other than zero is returned.
exp(-("Distance" ** 2) / (2 * ([Sigma]**2)))
My understanding of maths is fairly basic so if this could be explained in Layman's term that would be great.