Adding a generic mathematical library

[Christopher Dimech]

> Sent: Sunday, July 21, 2024 at 5:19 PM
> From: "Emanuel Berg" <incal@dataswamp.org>
> To: emacs-devel@gnu.org
> Subject: Re: Adding a generic mathematical library
>
> Richard Stallman wrote:
>
> >> but I also have a math.el which I yank below if any of it
> >> can be used.
> >
> > Most of the fnctions in this library are very close
> > to trivial.
>
> Oh, my! Eli thinks they are so exotic only I use them, RMS
> thinks they are close to trivial.
>
> But I have many more files, I'll see what I have that can
> maybe impress you and Eli more.

We should ask the community what tools they would like to use,
whether combinatorics, random numbers (Gaussian, Bernoulli, Binomial), ...

May I suggest "Units and Conversions".  "Symbolic Simplification"
could also be a candidate.

To promote a mathematical library in Emacs and ensure its broad adoption,
we can think of some things outside the realm of your libraries but which
others would appreciate.

> I have already showed you math.el and perm.el, here are two
> more. But I'll look thru it all some other day and make
> a directory with all of them.
>
> ;;; -*- lexical-binding: t -*-
> ;;
> ;; this file:
> ;;   https://dataswamp.org/~incal/emacs-init/stats.el
>
> (require 'cl-lib)
>
> (defun decade ()
>   (interactive)
>   (cl-loop
>     with entries = ()
>     for d from 190 to 202
>     do (push (how-many (format "^.\\{14\\}%d[[:digit:]]" d)) entries)
>     finally (message "%s" (nreverse entries)) ))
>
> (defun random-distribution (n sum &optional min no-error)
>   "Return a list of N random numbers.
> \nThe sum of the numbers is SUM.
> \nEvery number is at least MIN. (default: 0)
> \nIf NO-ERROR, recompute unsolvable systems with MIN = 0. (default: nil)"
>   (or min (setq min 0))
>   (let ((min-share (* n min)))
>     (if (< sum min-share)
>         (if no-error
>             (random-distribution n sum)
>           (error "Bogus indata, unsolvable") )
>       (let ((vals (make-list n min))
>             (pool (- sum min-share)) )
>         (cl-loop while (< 0 pool)
>                  do (cl-incf (nth (random n) vals))
>                     (cl-decf pool) )
>         vals) )))
>
> (defalias 'rd #'random-distribution)
>
> ;; (apply #'+ (rd 10 100 3)) ; sum is 100, OK
> ;; (rd 10 100)               ; omitted/default min = 0, OK
> ;; (rd 10 100 10)            ; border case, but OK
> ;; (rd 10 100 20)            ; error: Bogus indata, unsolvable
> ;; (rd 10 100 20 t)          ; unsolvable but no-error, recompute for min = 0
> ;;
> ;; 10 example distributions for
> ;; n = 10, sum = 100, and min = 3,
> ;; i.e. (rd 10 100 3):
> ;;
> ;;   (12  8  8 10  7  6 19  9  7 14)
> ;;   ( 8 12  7 12  9 10  9  9 12 12)
> ;;   (14  6 15 11  9  9  6  8 11 11)
> ;;   ( 8 12  7  9 10  9 10 13 10 12)
> ;;   (12 12 15  6 10  8  6 10 14  7)
> ;;   ( 9  7 10  8 11 10  9 10 13 13)
> ;;   ( 7 13 13 10 13 10  5 13  5 11)
> ;;   (13  8  6  9 13  8 11  7 10 15)
> ;;   ( 7 10  5  6 17 14  8 10 14  9)
> ;;   (11 10  8  9 11 10 14 11  8  8)
>
> (provide 'stats)
>
> ;;; -*- lexical-binding: t -*-
> ;;
> ;; help from:
> ;;   https://codereview.stackexchange.com/q/186840
> ;;
> ;; this file:
> ;;   https://dataswamp.org/~incal/emacs-init/str-to-bits.el
>
> (require 'esh-util)
>
> (defun num-to-bits (num)
>   (let ((s ""))
>     (while (> num 0)
>       (setq s (concat (number-to-string (logand num 1)) s))
>       (setq num (ash num -1)) )
>     (if (string= "" s)
>         "0"
>       s) ))
>
> (defalias 'dec2bits  #'num-to-bits)
> (defalias 'char2bits #'num-to-bits)
>
> (defun str-to-bits (str &optional delim)
>   (interactive "sString: ")
>   (or delim (setq delim " "))
>   (let ((bits))
>     (dolist (c (string-to-list str) (mapconcat #'eshell-stringify bits delim))
>       (push (num-to-bits c) bits) )))
>
> ;; (str-to-bits "What's up Emacs community?") ; 111111 1110000 1110101 [...]
>
> (provide 'str-to-bits)
>
> --
> underground experts united
> https://dataswamp.org/~incal
>
>
>