search

ziotom78 / Healpix.jl

Healpix library written in Julia
GNU General Public License v2.0
53 stars 18 forks source link

Enquiry about smoothing maps #116

Open aniket-nath opened 1 month ago

aniket-nath commented 1 month ago

Hi, If I need to smooth a simulated map, is there any function that smooths out the map when given as input, or I need to take in account for the beam in the input cl for synfast itself?

LeeoBianchi commented 1 month ago

Hi, @ziotom78 will correct me if I am wrong, but I believe applying the beam to the C_l before synfast is definitely the most straightforward way to do it.

aniket-nath commented 1 month ago

But if I want to smooth a given map, then how should I proceed?

Aniket Nath School of Physical Sciences

On Thu, 26 Sep 2024 at 12:37 PM, Leo Alessandro Bianchi < @.***> wrote:

Hi, @ziotom78 https://github.com/ziotom78 will correct me if I am wrong, but I believe applying the beam to the C_l before synfast is definitely the most straightforward way to do it.

— Reply to this email directly, view it on GitHub https://github.com/ziotom78/Healpix.jl/issues/116#issuecomment-2376104039, or unsubscribe https://github.com/notifications/unsubscribe-auth/AXRXQ62ETW2AAGI2TW7T4L3ZYOXBZAVCNFSM6AAAAABO4JYNSSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDGNZWGEYDIMBTHE . You are receiving this because you authored the thread.Message ID: @.***>

LeeoBianchi commented 1 month ago

In that case I think it is best to proceed as follows:

  1. compute first the a_lm coefficients of your map through the SHT map2alm,
  2. apply the smoothing beam to the a_lms through almxfl,
  3. go back to the map space through an alm2map transform.

I hope this helps :)

aniket-nath commented 1 month ago

Hi, I have another question adding to this. What is the function corresponding to healpy.sphtfunc.alm2map_der1 function in the healpix python library? Or is there some other way to achieve that in the julia package?

ziotom78 commented 1 month ago

Hi, I have another question adding to this. What is the function corresponding to healpy.sphtfunc.alm2map_der1 function in the healpix python library? Or is there some other way to achieve that in the julia package?

Please avoid changing the subject of the issue, this one was related to map smoothing. I see you have asked this in #117 , let's continue the discussion there.