c6mekl, c6vmekl, c6pmekl, c6pvmkl: differential emission measure using Chebyshev representations with multi-temperature mekal

c6mekl is a multi-temperature mekal or apec model using sixth-order Chebyshev polynomial for the differential emission measure. The DEM is not constrained to be positive.. The switch parameter determines whether spectrum is calculated by running the mekal code, by interpolating on a pre-calculated mekal table, or using the apec model. The final option is now preferred. The reference for this model is Singh et al. (1996, ApJ, 456, 766).

c6pmekl differs by using the exponential of the 6th order Chebyshev polynomial

c6mekl and c6pmekl use abundances relative to the Solar abundances set by the abund command.

The variants c6vmekl and c6pvmkl with polynomial and exponential polynomial respectively allow the user to specify 14 elemental abundance.

For c6mekl and c6pmekl the parameters are:

par1-6	Chebyshev polynomial coefficients
par7	H density (cm$^{-3}$)
par8	abundance wrt to Solar
par9	Redshift
par10	Switch (0 = calculate, 1 = interpolate, 2 = interpolate using APEC model).
norm	Normalization

While for c6vmekl and c6pvmkl the parameters are:

par1-6	Chebyshev polynomial coefficients
par7	H density (cm$^{-3}$)
par8-21	Abundances of He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni wrt Solar (defined by the abund command)
par22	Redshift
par23	Switch (0 = calculate, 1 = interpolate, 2 = interpolate using APEC model).
norm	Normalization