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OK but what are the legitimate reasons to spell out Greek letters? Usually, they're already a shorthand for something else that has a name, so you should use th

OK but what are the legitimate reasons to spell out Greek letters? Usually, they're already a shorthand for something else that has a name, so you should use that name instead.

yesenadam 6y ago
One nice thing about Julia is being able to use Unicode characters in variable/constant names, e.g. π and θ, instead of the usual pi and theta, in programs.
- enriquto 6y ago
  you can also do this in python, perl and C (if you use gcc or clang)
- layer8 6y ago
  Most popular programming languages have that ability. The problem is that most people don’t know how to enter characters that aren’t on the keyboard and don’t have software installed/configured that makes it easy to do so (e.g. using a Compose key).
  - yesenadam 6y ago
    Ok, good to know. Well, Julia doesn't have those problems – in the REPL, out of the box, type "\pi[TAB]" for the greek letter, etc. And not needing an explicit multiplication sign in some places also makes mathematical code look more like maths, e.g. julia> 2π 6.283185307179586
    - AlbertoGP 6y ago
      Same with Emacs if you select the TeX input method: Alt-x set-input-method TeX \pi → π That works for any programming language. I’ve used it occasionally for my own programs but use plain ASCII if I expect others to work on the code.
gjm11 6y ago
In geometry, it's conventional to use Greek letters for angles. If you have two angles, theta/phi or alpha/beta are reasonable names for them. Probably better than angle1/angle2 (in which the names are mostly "noise"), but if the angles play specific roles then it may be better to use informative names: azimuth/altitude or whatever. In finance, there are lots of traditional Greek-letter names. Using gamma/delta/theta is probably _more_ immediately comprehensible to your audience than, say, secondOrderUnderlyingSensitivity/underlyingSensitivity/timeDerivative. (Of course, in this case you don't get to choose which Greek letters you use.) There are other contexts where particular Greek-letter names are traditional. Again, usually you don't get to choose which ones you use (at least, not if you want to get any familiarity advantage from using them). When doing algebraic manipulations, sometimes it's convenient to give one set of variables Latin-letter names and another "parallel" set corresponding Greek-letter names. E.g., if you're doing plane geometry, maybe one point is (x,y) and another is (xi,eta). In software, this is probably a strictly worse strategy than calling them (x1,y1) and (x2,y2) or something of the sort.
- exporectomy 6y ago
  I see. I had blinkers on for engineering which has symbols like nu for Poisson's ratio and epsilon for strain and I've developed some annoyance working with source code that's full of spelled out Greek letters where it's not even clear what they represent. Now I think about it, there are cases like you identified from finance where the Greek letter becomes the mainly known name, such as alpha and beta for Rayleigh damping coefficients. When implementing algorithms from literature, I've sometimes named variables with both - the description to aid understanding and the letter to make it clear how it corresponds to the original material. Still don't get to choose the letter though.
trombonechamp 6y ago
Two examples of times I have used Greek letter variable names: (a) Often times the Greek letter is the standard way of referring to a concept, e.g. "beta" in a linear regression. For these situations, the Greek letter would be used in spoken language to refer to the concept and is more clear than trying to describe the underlying concept in English. (b) If you implement a non-trivial mathematical equation, it is clearer to use the variable names which are found in the published equation than to try to rename them. To understand the equation, people will need to read the published description anyway, and it is easier to map one to the other if you don't change the names. Likewise, if you are implementing your own equation, you will usually use Greek letters in the paper, and for consistency, you should use the same variable names in the code as you do in your paper.

OK but what are the legitimate reasons to spell out Greek letters? Usually, they're already a shorthand for something else that has a name, so you should use that name instead.

yesenadam 6y ago

One nice thing about Julia is being able to use Unicode characters in variable/constant names, e.g. π and θ, instead of the usual pi and theta, in programs.

enriquto 6y ago
you can also do this in python, perl and C (if you use gcc or clang)
layer8 6y ago
Most popular programming languages have that ability. The problem is that most people don’t know how to enter characters that aren’t on the keyboard and don’t have software installed/configured that makes it easy to do so (e.g. using a Compose key).
- yesenadam 6y ago
  Ok, good to know. Well, Julia doesn't have those problems – in the REPL, out of the box, type "\pi[TAB]" for the greek letter, etc. And not needing an explicit multiplication sign in some places also makes mathematical code look more like maths, e.g. julia> 2π 6.283185307179586
  - AlbertoGP 6y ago
    Same with Emacs if you select the TeX input method: Alt-x set-input-method TeX \pi → π That works for any programming language. I’ve used it occasionally for my own programs but use plain ASCII if I expect others to work on the code.

gjm11 6y ago

In geometry, it's conventional to use Greek letters for angles. If you have two angles, theta/phi or alpha/beta are reasonable names for them. Probably better than angle1/angle2 (in which the names are mostly "noise"), but if the angles play specific roles then it may be better to use informative names: azimuth/altitude or whatever. In finance, there are lots of traditional Greek-letter names. Using gamma/delta/theta is probably _more_ immediately comprehensible to your audience than, say, secondOrderUnderlyingSensitivity/underlyingSensitivity/timeDerivative. (Of course, in this case you don't get to choose which Greek letters you use.) There are other contexts where particular Greek-letter names are traditional. Again, usually you don't get to choose which ones you use (at least, not if you want to get any familiarity advantage from using them). When doing algebraic manipulations, sometimes it's convenient to give one set of variables Latin-letter names and another "parallel" set corresponding Greek-letter names. E.g., if you're doing plane geometry, maybe one point is (x,y) and another is (xi,eta). In software, this is probably a strictly worse strategy than calling them (x1,y1) and (x2,y2) or something of the sort.

exporectomy 6y ago
I see. I had blinkers on for engineering which has symbols like nu for Poisson's ratio and epsilon for strain and I've developed some annoyance working with source code that's full of spelled out Greek letters where it's not even clear what they represent. Now I think about it, there are cases like you identified from finance where the Greek letter becomes the mainly known name, such as alpha and beta for Rayleigh damping coefficients. When implementing algorithms from literature, I've sometimes named variables with both - the description to aid understanding and the letter to make it clear how it corresponds to the original material. Still don't get to choose the letter though.

trombonechamp 6y ago

Two examples of times I have used Greek letter variable names: (a) Often times the Greek letter is the standard way of referring to a concept, e.g. "beta" in a linear regression. For these situations, the Greek letter would be used in spoken language to refer to the concept and is more clear than trying to describe the underlying concept in English. (b) If you implement a non-trivial mathematical equation, it is clearer to use the variable names which are found in the published equation than to try to rename them. To understand the equation, people will need to read the published description anyway, and it is easier to map one to the other if you don't change the names. Likewise, if you are implementing your own equation, you will usually use Greek letters in the paper, and for consistency, you should use the same variable names in the code as you do in your paper.