gsmooth: gaussian smoothing

Gaussian smoothing with a variable width $\Sigma(E)$, which varies as the par2 power of the energy. The width at 6 keV is set with par1. Note that the energy binning must be uniform. If the response energies are not uniformly spaced then the energies command should be used to set uniform energy binning.

$$dC(E) = \frac{1}{\sqrt{2\pi\Sigma(E)^2}}\exp\left[-\frac{1}{2}\left(\frac{E-X}{\Sigma(E)}\right)^2\right]A(X)dX$$

$$\Sigma(E) = \sigma(E/6)^\alpha$$

where:

par1=$\sigma$	gaussian sigma at 6 keV
par2=$\alpha$	power of energy for sigma variation