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4:32 AM
Quick question, how do I turn {{a,b},{c,d}} into {{1/a,b},{1/c,d}}? My attempt to use the documentation "Map" only turns it into {{1/a,1/b},{1/c,1/d}}
 
5:14 AM
@Allure Try MapAt[1/# &, {{a, b}, {c, d}}, {All, 1}].
 
5:33 AM
Thanks, now to figure out the syntax :)
I get the syntax - thanks again!
 
 
6 hours later…
11:53 AM
is there any way to integrate this?
 
 
2 hours later…
2:09 PM
I have this workflow problem. I have some "tutorials" or lecture notes written in .nb files. When I teach from them, changes/revisions occur to me, some of which might not be simple or quick. In TeX, I can make metanotes in comments in the source file. It's convenient to have the notes embedded in the file and invisible to the end user. I'm not sure how to do the same thing in Mma. I could write a function that would strip out certain cell styles and save the NB in a new destination.
I'm wondering if there's some functionality I'm missing.
Because of this, I often just write in TeX. But sometimes it's nice to have code that students can use to explore right there.
 
3:02 PM
In computing the phase of a 2DFFT, or 3DFFT, I encounter ArcTan[0,0] which throws errors like crazy. I think there’s either an algorithmic workaround, or something I can add to the pattern matching possibly, to manage for this. Any recommendations?
@MichaelE2 do the students access these in real time? It doesn’t seem to me there’d be an issue with adding into a collapsed cell when you present them, but if you’re looking to just add these notes and leave them there, I am thinking you could do something like showing the raw code of a cell by (iirc) Ctrl+Shift+E and then adding a comment via a comment, then un-unhide the raw code by the same key shortcut as before? Not so super hidden/inaccessible, but I think it could help to manage it
 
@CATrevillian you can replace ArcTan[x, y] with Arg[x + I y] for the desired behavior at zero.
 
3:20 PM
@J.M.willbebacksoon aha! Very simple. Is there any reason I should not just use that instead?
 
@CATrevillian You can differentiate ArcTan[], but Arg[] is tricky. I'm sure there are other reasons I am missing.
 
@CATrevillian The thing is, that for a complex number, the phase has no defined direction at 0.
 
3:37 PM
@CATrevillian The notes I want to add are of the form "It would be helpful if there were an example that did X" or "Consider moving this section to follow that section" and other sorts of problems with the writing. They come up from the kinds of questions students have, the mistakes they make, where they get stuck, etc. It just feels like one's underwear is showing if you leave them there. Sometimes I see the problem but the solution might elude me for a while.
I could do these things through Git I suppose and treat them like bugs. But I don't really know how to use Git....
 
3:56 PM
@halirutan that may likely work in my advantage, as I would just like to color a graphic with the phase values in grayscale? Inevitably actually it would be sweet to apply this to some micromagnetics! But that’s not the intended outcome here. If I don’t lose any value of quadrant positioning using Arg, that may be my answer to simplistically manage for the 0 issue using ArcTan.
 
so something like the color wheel, except gray?
 
@J.M.willbebacksoon mayhaps that will be valuable, to differentiate the phase, if I am ever encountering something like a TDFFT or TRFFT but I don’t think we get to that in the course of the course. Not entirely, but maybe actually, a color wheel except gray, although it seems to me when you plot the phase of a fast Fourier transform that you get something rather unintelligible and wholly uninteresting if only for a verification of yes the Wolfram Language Can (too)
@MichaelE2 Git is very valuable! I want to implement some gradebooks in a git repo, so that multiple TAs can edit and then commit their changes. Git would track who alters what, and provide a history useful to those in administration that want to care about that. Is there a reason perhaps that you couldn’t do something like have a cell in your version that is specifically removed when you export it to the distributable version?
 
 
2 hours later…
6:45 PM
@MichaelE2 Why not use Presentation and Working screen style environments, and have a cell style that only shows up in the Working screen style environment?
 
 
1 hour later…
8:01 PM
@CarlWoll Thanks. (1) I didn't know that was possible. Do you use CellOpen -> False? (2) I don't really use the notebooks for presentation. I expect the students to read them as homework, which I assume they'd do in the Working environment. When I project anything in class, it is either static info that is referred to throughout the class period or an example usually wrapped in a Manipulate. I don't really face the same issue maintaining them.
 
 
2 hours later…
9:40 PM
@MichaelE2 Lots of ways this can be done in the notebook's Stylesheet
I often make an Editing style environment and then display in Working if I expect people to use them
This is how I do my documentation notebook stylesheets
Check out what the Metadata style does
 
 
2 hours later…
11:58 PM
@b3m2a1 The Metadata style seems the ticket. I guess we can have arbitrarily named screen environments -- I didn't know.
 

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