Re: ideas about representing degrees as Maxima expressions

On Fri, May 1, 2026 at 3:54 PM Stavros Macrakis <[email protected]> wrote:

> On Thu, Apr 30, 2026 at 12:43 AM Robert Dodier <[email protected]> wrote:

>> modulo 360. This last bit produces degrees(-10) --> degrees(350).

> Really? Why are you doing modular arithmetic on degrees?

I guess that doesn't really make much sense. I will cut out that bit
and try it again.

> I'd think you want a global option for how to present them: fractional degrees or degrees/minutes/seconds.

Well, so far I am assuming that the user inputs stuff the way they
want to see it, either as degrees only or degrees with minutes or
minutes and seconds. For purely numerical values, a canonical
representation as just one number is workable, but when variables are
allowed, as I think they must be, then I don't see a way to make that
work.

E.g. suppose a user writes degrees(x, y, z) so the canonical
representation could be either x + y/60 + z/3600 (degrees) or x*3600 +
y*60 + z (seconds). That seems to make a mess when you try to extract
bits for display; Maxima doesn't recover x from floor((x + 60*y +
3600*z)/3600), even after assuming that y and z are >= 0 and < 60.
Maybe I'm overlooking something obvious.

> How do you handle the inverse functions? i.e. how do you get asin(1/2) => 30° ? Is that degrees(asin(1/2))?

Almost. It has to be degrees(from_radians(asin(1/2))) since asin(1/2)
is just a number, so degrees(asin(1/2)) is valid and it represents
%pi/6 degrees.

best

Robert


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