CosmoMC:How to set re_use_optical_depth and value of re_optical_depth in MCMC?
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- Posts: 22
- Joined: January 02 2005
- Affiliation: SISSA, Italy
CosmoMC:How to set re_use_optical_depth and value of re_opti
Dear all,
In CAMB I can set re_use_optical_depth and re_optical_depth in ./CAMB/params.ini
re_use_optical_depth = T
re_optical_depth = 0.04
But When I use MCMC, I don't know how to set these two parameters.
And if I don't modify anything the default is
re_use_optical_depth = F
re_optical_depth = 0
Now I want to set these two parameters
re_use_optical_depth = T
re_optical_depth = 0.04
How to do this?
Thanks!
Jun-Qing Xia
In CAMB I can set re_use_optical_depth and re_optical_depth in ./CAMB/params.ini
re_use_optical_depth = T
re_optical_depth = 0.04
But When I use MCMC, I don't know how to set these two parameters.
And if I don't modify anything the default is
re_use_optical_depth = F
re_optical_depth = 0
Now I want to set these two parameters
re_use_optical_depth = T
re_optical_depth = 0.04
How to do this?
Thanks!
Jun-Qing Xia
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- Posts: 5
- Joined: October 06 2004
- Affiliation: Helsinki Institute of Physics
- Contact:
CosmoMC:How to set re_use_optical_depth and value of re_opti
Hi.
When you're running CosmoMC the 'params.ini' for CAMB, i.e., the one in /CAMB, is not used at all.
Instead, the values for the parameters are given in the 'params.ini' for CosmoMC.
In case of fixed optical depth, \tau=0.04, you just set 'param4' in 'params.ini' to 0.04 0.04 0.04 0 0.
Actually, the min and max values (2nd and 3rd number) can be anything, as long as 0.04 is
in that interval and the start and propose widths are zero so that \tau doesn't wander away from
its starting position. This of course works similarly for all the other parameters as well.
Hope this helps.
Vesa
When you're running CosmoMC the 'params.ini' for CAMB, i.e., the one in /CAMB, is not used at all.
Instead, the values for the parameters are given in the 'params.ini' for CosmoMC.
In case of fixed optical depth, \tau=0.04, you just set 'param4' in 'params.ini' to 0.04 0.04 0.04 0 0.
Actually, the min and max values (2nd and 3rd number) can be anything, as long as 0.04 is
in that interval and the start and propose widths are zero so that \tau doesn't wander away from
its starting position. This of course works similarly for all the other parameters as well.
Hope this helps.
Vesa
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- Posts: 22
- Joined: January 02 2005
- Affiliation: SISSA, Italy
CosmoMC:How to set re_use_optical_depth and value of re_opti
Hi,
If I set the param4 like this
param4 = 0 0 0 0 0
will the parameter re_use_optical_depth be set as F automatically?
And when setting param4 = 0.17 0.01 0.8 0.07 0.04
re_use_optical_depth will be change to T automatically?
Thanks!
Jun-Qing Xia
If I set the param4 like this
param4 = 0 0 0 0 0
will the parameter re_use_optical_depth be set as F automatically?
And when setting param4 = 0.17 0.01 0.8 0.07 0.04
re_use_optical_depth will be change to T automatically?
Thanks!
Jun-Qing Xia
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- Posts: 1943
- Joined: September 23 2004
- Affiliation: University of Sussex
- Contact:
Re: CosmoMC:How to set re_use_optical_depth and value of re_
In the first case it sets tau to zero (so more like use_optical_depth=F; z_re=tau=0).
The default CosmoMC parameterization always uses the optical depth, not reionization redshift (so internally it does set re_use_optical_depth=T, yes). See the alternative params_H download in the readme if you want to use z_re instead.
The default CosmoMC parameterization always uses the optical depth, not reionization redshift (so internally it does set re_use_optical_depth=T, yes). See the alternative params_H download in the readme if you want to use z_re instead.