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Against the odds, APL's logarithm wins | Chasing Men Who Stare at Arrays

Against the odds, APL’s logarithm wins

APL film logo

You probably noticed there were two choices on the voting ballot for the APL film logo, and logarithm wasn’t one of them. In fact, the APL symbol for rotate lead with 71% before we closed the poll – You might ask: What happened?

The first thing that happened immediately was a strong constituency lobbying for the APL symbol lamp.  Lamp is the symbol which denotes a comment in APL, and on the surface this is an obvious choice for a film logo.  In fact, lamp was on the list of possibilities presented to Cris Jaw, our visionary leader in the design process. While lamp simply isn’t badass enough for me, we heard the passion in the voices of our critics.   The discourse opened the door to the possibility that there might be a better choice than the two up for vote.  So, when APL’s logarithm was put forward later in the discussion which followed we had already considered the idea of not going with the vote.

The most compelling reason for going with APL’s symbol logarithm is:

It it denotes a function for which conventional mathematical notation does not have a good symbol (see Roger Hui’s, My Favorite APL Symbol 2013).

What better reminder that Kenneth E. Iverson’s vision was always turned to the future than an APL symbol to remind us that computer languages aren’t perfect, and neither is mathematical notation.   In the continuum of human progress, we’re not done yet.

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12 Responses to “Against the odds, APL’s logarithm wins”


  • That’s great! The circle star is my favorite APL character. Thank you for the link to Roger’s article, which explains how the circle star worked its way into my heart and includes reasons I never thought of!

    This spring San Jose State University is starting to use a new learning management system. (It’s Canvas, and if you don’t know what an LMS is, don’t worry about it!) We can upload a picture to go next to our name, as in Linkedin and Facebook. I decided to upload a big circle star instead of a photograph. So far, nobody has asked me about it, but it’s still early in the semester. I did spend a while looking for one I liked, since a pointy star in a circle when it’s enlarged looks like some kind of an evil sheriff’s badge. I think I took mine from the “APL2 Unicode” font with a star that’s anything but pointy.

  • P.S. When I went to close Roger’s “My Favorite APL Symbol” http://www.jsoftware.com/papers/log.htm I noticed he used a not-very-pointy star that is very close to the one I chose. But this is a digression! For the film logo, I think the artists should choose what looks best in the logo – so long as it has the right number of points.

  • aprogramminglanguage aprogramminglanguage

    Well Curtis, it turns out there isn’t an 100% correct number of points.

    In fact, it was Simon Garland who pointed out that we could also have gone with 6 points in our design.

    http://en.wikipedia.org/wiki/APL_(codepage)

    We chose 5 because it looks better and we can see in a photo that Hal Carim posted in Facebook, a type ball with a star with 5 points…

    http://www.chastney.com/~philip/SImPL/APL_fonts_are_different.pdf

    And besides, to quote a story told by Jon McGrew – “We have the Arabs to thank for zero.”

  • Not quite on topic, but I am disappointed that your CAPCHA code is just alphanumeric and doesn’t include APL characters – type in an APL one-liner in Unicode to prove you’re not a bot.

  • aprogramminglanguage aprogramminglanguage

    Dear John,

    Make me a WordPress plugin and I’ll turn it on.

    Thanks for reading.

  • > And besides, to quote a story told by Jon McGrew –
    > “We have the Arabs to thank for zero.”

    The story is better than your quote indicates. From http://www.jsoftware.com/papers/APLQA.htm#nothing:

    • [Commenting on the empty vector:] I think we have the Arabs to thank for inventing zero, but I know that we have Dr. Iverson to thank for inventing nothing.

    — Donald McIntyre, APL Users Meeting, 1980-10

  • A great choice Catherine. Just yesterday I was staring at this very symbol in some old APL logarithmic regression code that I am converting to C#. The beauty of circle star is nowhere to be seen in C#, but, with the increasing use of Unicode, elegant symbols are making their way into many languages. In another generation APL will not be seen as strange.

  • aprogramminglanguage aprogramminglanguage

    Dear John, THAT is so cool.

    Heh… Roger, you paper http://www.jsoftware.com/papers/log.htm is generating more buz an excitement than my logo. Nice job!

  • Discussion of the lamp symbol reminds me of a point from the early APL Language Manual from IBM (GC26-3847, circa mid-1970s). This was of course a serious formal manual, but I believe that it was Adin Falkoff who provided its one and only brush with humor: Under the COMMENTS heading, the manual explains that “The lamp symbol (the cap-null) signifies that what follows it is a comment, for illumination only and not to be executed…”. I have always liked the idea that the lamp is for illumination. Of course.

    I also want to extend thanks to Roger for clarifying the discussion about zero and empty vectors. The quote was indeed from Donald McIntyre. I thought that Donald’s comment was brilliant, and I would certainly never claim any credit for that.

  • Jon, I found an earlier reference for the comment on the comment symbol in the APL\360 User’s Manual, 1968-08, page 3.45:

    Comments: The lamp symbol ⍝, formed by overstriking ∩ and ∘, signifies that what follows it is a comment, for illumination only and not to be executed; it may occur only as the first character in a statement, but may be used in defined functions.

    The manual has at least one other “brush with humor”, depending on your sense of humor. Figure 1.2 depicts an APL\360 keyboard (which has a 5-pointed rather than 6-pointed star, by the way), accompanied with the following paragraph:

    The special characters, most of which are produced with the keyboard shifted, generally have some mnemonic connection with their alphabetic or numeric correspondents. This may be appearance (⍵ over W), Greek-Roman equivalence (⍴ over R), sequence ( ≠ over 3 4 5 6 7 8), or some — possibly far fetched — relationship between the APL function represented by the symbol and the letter (* over P for power, ‘ over K for “kwote”, and ⌈ over S for ceiling).

    Seems pretty hilarious to me.

  • Andrew W. Fornallaz

    Good choice.

  • I remember back in the mid 1970s, my Dad who worked for IBM in San Jose came home with a zipper bag designed to hold documents about APL which he was working on at the time. The bag said “APL A Programing Language” and there was a logo graphic of an apple, almost identical to the one Apple Computer later used. I am pretty sure it was before Apple Computer began using their apple logo. I think it had horizontal rainbow stripes, but no bite. When I later saw Apple Computer’s logo I thought they were related or that they had taken the idea for their logo from the APL logo used on that bag. Food for thought.

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