From: vanhoof@cita.utoronto.ca
Sent: Monday, July 26, 1999 6:58 PM

Hi Gary,

Below I will go through the changes I made in version 84 of Cloudy. I will
use the same sequence as in the appendix of my thesis. This file is intended
as an addition to the discussion in my thesis and both should be read together.
For each command I will indicate my assessment of the importance of the command.

1. distance 21.85 [vary]

Very useful for allowing the user to supply fluxes in natural units
(i.e. as observed) and allowing Cloudy to generate output that is
normalized in a more natural way (i.e. spectra and line fluxes normalized
at earth distance). This command is necessary when one wants to optimize
an observed flux and simultaneously wants to vary the inner radius.

Priority: high

2. dlaw <n1> <n2> [vary]

At present it is not possible to use the keyword vary, although this
may very well be useful.

Priority: high

3. dtable [use full range]

Is implemented as "dlaw table". However the option "full range" is not
implemented. This sets the inner and outer radius of the nebula to the
start and end radius supplied in the table. This is convenient when the
table is produced by an external program and the inner and outer radius
may vary from run to run.

Priority: medium

4. element helium 11.02

Is mostly implemented in Cloudy 90. However the normalization of the
abundance scale cannot be altered, although several normalizations are
in use.

Priority: high

5. flunit herz [at earth distance]

Allows the user to choose other flux units for the spectrum and to normalize
fluxes at the earths distance. See also point 1.

Priority: high

6. frunit micron

Allows the user to choose the frequency unit for his plot

7. grains .... [log], [vary]

The keywords log and vary are not included now.

Priority: high

8. minimum electron temperature 10K

Was needed in Cloudy 84 to assure stability far out in the cold part of the
nebula. I am not sure if it is still needed in Cloudy 93

Priority: ??

9. optimize amoeba

No action necessary.

10. optimize angular diameter

Combined with the distance, this allow further constraints on the model.

Priority: high.

11. optimize color temperature

Was introduced when optimizing on IRAS fluxes introduced unstable behavior.
Was later abandoned again.

Priority: low.

12. optimize continue

Is already implemented for phymir. It could also be implemented for the other
optimizers.

Priority: low.

13. optimize far-infrared flux

Is roughly similar to optimizing on GraT 0 (although not completely, this
command includes all emission at IR wavelengths, not just grain emission).
See also point 11.

Priority: low.

14. optimize flux 3 cm 6 mJy

Very useful for optimizing continuum fluxes, e.g. IR grain emission or
radio flux.

Priority: high.

15. optimize intensity -12.26

Different normalization, see point 1.

Priority: high.

16. optimize lines:
    IRAS 60 ....

All kinds of photometric bands were added to Cloudy 84. These are very
informative by themselves and probably should be added to Cloudy. I also
allowed for the possibility to optimize on fluxes observed in these bands,
but found that to be less useful (although not useless). It can introduce
instabilities because the code can exchange continuum flux for line flux.
This can lead to absurd abundances.

Priority: high (for inclusion in output)
          low to medium (for optimizing)

17. optimize phymir

Already included.

18. optimize tolerance

Already changed.

19. plot commands

They were very useful, but it is not clear whether they are suitable for
distribution since my plot system is based on idl.

Priority: low

20. print verbose

The default and the exception for printing every iteration/only the last
iteration is switched. A matter of taste...

Priority: low.

21. punch emissivity

Very useful when you want to use a separate code which does proper radiative
transport of diffuse continua in optically thick conditions. I have a code
which does this (neglecting scattering).

Priority: medium

22. punch extended spectrum

Is automatically implemented now with the extension of the radio continuum
in Cloudy. Hence no action is necessary.

23. rfac 3.

Was introduced to solve problems with the "radius 17.0 17.5 vary" command
(the optimizer could let the inner radius go outside the outer radius).
Apart from this problem, the command is obsolete now.

Priority: low.

24. runit parsec

Allows the user to chose a radius unit for the punch output. See also point
5 and 6.

Priority: high

25. set drmax 0.01 relative

Prevent the code from taking very big steps outwards. Allows for a more
precise integration outwards and may make the chi^2 function smoother
when optimizing.

Priority: medium

26. silent

Turn off all optimizer output for intermediate iterations. Only the initial
messages and the final model are printed. Useful for people with limited
disk space (they still exist !).

Priority: medium

27. single iteration

Is like the "no vary" command, except that it produces the chi^2 information
at the end of the file. Useful for doing a short test of the input file.
Using "optimize iterations 0" doesn't work, since the number is defaulted
to 1 and therefore the model is executed twice. The command "no vary" could
be altered to include this possibility.

Priority: medium

28. stop flux at 5.9 cm 93 mJy

I do not use it at the moment. I am not sure whether it is useful.

Priority: low

29. stop [ionized] mass 0.2

I do not use it at the moment. I am not sure whether it is useful.

Priority: low

30. stop photometry IRAS 60 23 Jy

I use this command for defining an outer radius in the neutral zone, for
lack of anything better... Could be altered to something like "stop
continuum flux at 60 micron 23 Jy" which would be easier to implement.

Priority: high

31. sublimation radius 17.25

Since Cloudy allows for a varying D/G ratio as a function of radius, this
is command is obsolete now.

32. sublimation temperature 1500K

Force grains to exist only there where the equilibrium temperature is below
a preset sublimation temperature. I think this command is still very useful.

Priority: high



I hope this is somewhat clear.... I also made changes to the output, some of
which may also be useful. I will discuss those at a later date.


Cheers,

Peter.


