Integer order 1D Gaussian function

Computes the Gaussian function in 1D:
exp(-log(2)*(2*(x-x0)./FWHM).^(2*floor(abs(order))));

Where:
x = Co-ordinate
x0 = Centre of function
FWHM = Full Width Half Max of the function
order = Gaussian order

Normal Gaussian is of order 1.

Note that FWHM = (1/e Half Width)/sqrt(2*log(2))
log is the natural log.