taskGNU Astronomy Utilities - Tasks: task #14697, cosmiccal documentation


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task #14697: cosmiccal documentation

Submitter:  Boud Roukema <boud>
Submitted:  Wed 18 Oct 2017 10:24:53 PM UTC
Should Start On:  Wed 18 Oct 2017 12:00:00 AM UTC Should be Finished on:  Tue 18 Oct 2022 12:00:00 AM UTC
Category:  Book Priority:  5 - Normal
Item Group:  Documentation Status:  In Progress
Privacy:  Public Assigned to:  boud
Percent Complete:  10% Open/Closed:  Open
Effort:  0.00

Thu 19 Oct 2017 07:20:53 PM UTC, comment #4: 

I also had a small request. With your great experience in this field, could you kindly add a few references in the last paragraph of the first paragraph? 

In particular, it would be great if you could add a footnote which introduces some books and webpages (Wikipedia maybe) in this sentence: "There are many references available for such reviews that go deep into the abstract mathematical proofs."

Sorry I forgot to include this request in the previous comment.

Mohammad Akhlaghi <makhlaghi>
Group administrator
Thu 19 Oct 2017 07:14:54 PM UTC, comment #3: 

Sorry, in the previous message, the address to the commit doesn't work. Here is the correct link.

Mohammad Akhlaghi <makhlaghi>
Group administrator
Thu 19 Oct 2017 07:13:31 PM UTC, comment #2: 

Thank you very much for the corrections Boud. They have now been pushed into the main repo.

The commit message describes the minor changes I made. I hope they are convincing for you. If not, maybe we can discuss them here and once we converge, we can put it into the manual.

My previous message on this thread might have caused some confusion, sorry for that. Gnuastro is not intended only for observers. Of course, we also hope that Gnuastro will to be useful for a theorist. In this particular case, a theorist is already fully versed in concepts and proofs, they will not be interested in such sections.

The people who will actually read this section are people who have not worked on the theory for a long time but need the results and just want to be reminded (an observer). Or someone who has just learnt the concepts in some textbook/course, has installed Gnuastro and wants to see how to interpret the outputs of CosmicCalculator without having to open their textbook again.

Thanks a lot for all the great suggestions to improve this important chapter :-).

Mohammad Akhlaghi <makhlaghi>
Group administrator
Wed 18 Oct 2017 11:20:19 PM UTC, comment #1: 

Thanks a lot Boud. Indeed Wikipedia exists and there are also many other books that provide the mathematical proofs. But the emphasis here is not on mathematical rigour, its on visualization/intuition for someone who is not too invested in theory, but needs to properly understand the outputs of the program: an observer.

Atleast when I was studying these subjects, I couldn't find any proper place to help in the visualization, everywhere I could find would jump so directly deep into the mathematics that even though I followed the equations and appreciated their abstract beauty, I could never actually visualize what I am doing or what all these concepts were. So I came up with this explanation (many years before creating Gnuastro).

The thing about Gnuastro is that it is not just a reference for abstract teaching or just a black-box software that throws out results. Gnuastro is actually the book+software: not just a book or not just a software.

I have fully described the philosophy/manifesto behind creating Gnuastro in the introduction (link below), I would really appreciate your thoughts on it (maybe as a separate task):


You see this in many other contexts throughout the book. For example here is a very long section on frequency domain convolution:


It starts with visualizing the complex plane and goes onto the fourier series and transform and sampling theory and etc. Observers (users of Gnuastro's convolve) need to understand these concepts (I have seen many who don't, they just know the equations, but have no intuition).

Another nice example in another context might be the introduction to libraries in the book:


Like the discussion above for curvature, all this information is available in other abstract teaching books (on digital signal processing and programming respectively), but I don't think that makes these sections redundant. Given the discussion in the "Science and its tools" section, does this convince you?

Ofcourse, we don't want the Gnuastro book to be a full encyclopedia, we can put links to references (books/wikipedia) for people interested in further reading to avoid going into too much detail in what ever context we are discussing.

Mohammad Akhlaghi <makhlaghi>
Group administrator
Wed 18 Oct 2017 10:24:53 PM UTC, original submission:  

Editing all the cosmiccal parts of gnuastro.texi would be a
huge amount of work, and in general I worry that this is
redundant with material that should be in Wikipedia or
Wikiversity (I don't see the point of Wikibooks for physics
education - text plus hardwired or non-WIMS based exercises are
not serious alternatives for learning physics), but I started
editing the "2D curved space" section, so I don't fully exclude
the possibility that I might make more edits.

Here is one new commit (on its own branch):


Boud Roukema <boud>
Group Member


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