1
Fork 0
mirror of git://git.sv.gnu.org/emacs.git synced 2026-01-03 02:31:03 -08:00
emacs/lisp/calc/calc-frac.el
Paul Eggert bc511a64f6 Prefer HTTPS to FTP and HTTP in documentation
Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November.  Change these FTP URLs to https://ftp.gnu.org
instead.  Make similar changes for URLs to other organizations moving
away from FTP.  Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.
2017-09-13 15:54:37 -07:00

235 lines
6.6 KiB
EmacsLisp

;;; calc-frac.el --- fraction functions for Calc
;; Copyright (C) 1990-1993, 2001-2017 Free Software Foundation, Inc.
;; Author: David Gillespie <daveg@synaptics.com>
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
;; This file is autoloaded from calc-ext.el.
(require 'calc-ext)
(require 'calc-macs)
(defun calc-fdiv (arg)
(interactive "P")
(calc-slow-wrapper
(calc-binary-op ":" 'calcFunc-fdiv arg 1)))
(defun calc-fraction (arg)
(interactive "P")
(calc-slow-wrapper
(let ((func (if (calc-is-hyperbolic) 'calcFunc-frac 'calcFunc-pfrac)))
(if (eq arg 0)
(calc-enter-result 2 "frac" (list func
(calc-top-n 2)
(calc-top-n 1)))
(calc-enter-result 1 "frac" (list func
(calc-top-n 1)
(prefix-numeric-value (or arg 0))))))))
(defun calc-over-notation (fmt)
(interactive "sFraction separator: ")
(calc-wrapper
(if (string-match "\\`\\([^ 0-9][^ 0-9]?\\)[0-9]*\\'" fmt)
(let ((n nil))
(if (/= (match-end 0) (match-end 1))
(setq n (string-to-number (substring fmt (match-end 1)))
fmt (math-match-substring fmt 1)))
(if (eq n 0) (error "Bad denominator"))
(calc-change-mode 'calc-frac-format (list fmt n) t))
(error "Bad fraction separator format"))))
(defun calc-slash-notation (n)
(interactive "P")
(calc-wrapper
(calc-change-mode 'calc-frac-format (if n '("//" nil) '("/" nil)) t)))
(defun calc-frac-mode (n)
(interactive "P")
(calc-wrapper
(calc-change-mode 'calc-prefer-frac n nil t)
(message (if calc-prefer-frac
"Integer division will now generate fractions"
"Integer division will now generate floating-point results"))))
;;;; Fractions.
;;; Build a normalized fraction. [R I I]
;;; (This could probably be implemented more efficiently than using
;;; the plain gcd algorithm.)
(defun math-make-frac (num den)
(if (Math-integer-negp den)
(setq num (math-neg num)
den (math-neg den)))
(let ((gcd (math-gcd num den)))
(if (eq gcd 1)
(if (eq den 1)
num
(list 'frac num den))
(if (equal gcd den)
(math-quotient num gcd)
(list 'frac (math-quotient num gcd) (math-quotient den gcd))))))
(defun calc-add-fractions (a b)
(if (eq (car-safe a) 'frac)
(if (eq (car-safe b) 'frac)
(math-make-frac (math-add (math-mul (nth 1 a) (nth 2 b))
(math-mul (nth 2 a) (nth 1 b)))
(math-mul (nth 2 a) (nth 2 b)))
(math-make-frac (math-add (nth 1 a)
(math-mul (nth 2 a) b))
(nth 2 a)))
(math-make-frac (math-add (math-mul a (nth 2 b))
(nth 1 b))
(nth 2 b))))
(defun calc-mul-fractions (a b)
(if (eq (car-safe a) 'frac)
(if (eq (car-safe b) 'frac)
(math-make-frac (math-mul (nth 1 a) (nth 1 b))
(math-mul (nth 2 a) (nth 2 b)))
(math-make-frac (math-mul (nth 1 a) b)
(nth 2 a)))
(math-make-frac (math-mul a (nth 1 b))
(nth 2 b))))
(defun calc-div-fractions (a b)
(if (eq (car-safe a) 'frac)
(if (eq (car-safe b) 'frac)
(math-make-frac (math-mul (nth 1 a) (nth 2 b))
(math-mul (nth 2 a) (nth 1 b)))
(math-make-frac (nth 1 a)
(math-mul (nth 2 a) b)))
(math-make-frac (math-mul a (nth 2 b))
(nth 1 b))))
;;; Convert a real value to fractional form. [T R I; T R F] [Public]
(defun calcFunc-frac (a &optional tol)
(or tol (setq tol 0))
(cond ((Math-ratp a)
a)
((memq (car a) '(cplx polar vec hms date sdev intv mod))
(cons (car a) (mapcar (function
(lambda (x)
(calcFunc-frac x tol)))
(cdr a))))
((Math-messy-integerp a)
(math-trunc a))
((Math-negp a)
(math-neg (calcFunc-frac (math-neg a) tol)))
((not (eq (car a) 'float))
(if (math-infinitep a)
a
(if (math-provably-integerp a)
a
(math-reject-arg a 'numberp))))
((integerp tol)
(if (<= tol 0)
(setq tol (+ tol calc-internal-prec)))
(calcFunc-frac a (list 'float 5
(- (+ (math-numdigs (nth 1 a))
(nth 2 a))
(1+ tol)))))
((not (eq (car tol) 'float))
(if (Math-realp tol)
(calcFunc-frac a (math-float tol))
(math-reject-arg tol 'realp)))
((Math-negp tol)
(calcFunc-frac a (math-neg tol)))
((Math-zerop tol)
(calcFunc-frac a 0))
((not (math-lessp-float tol '(float 1 0)))
(math-trunc a))
((Math-zerop a)
0)
(t
(let ((cfrac (math-continued-fraction a tol))
(calc-prefer-frac t))
(math-eval-continued-fraction cfrac)))))
(defun math-continued-fraction (a tol)
(let ((calc-internal-prec (+ calc-internal-prec 2)))
(let ((cfrac nil)
(aa a)
(calc-prefer-frac nil)
int)
(while (or (null cfrac)
(and (not (Math-zerop aa))
(not (math-lessp-float
(math-abs
(math-sub a
(let ((f (math-eval-continued-fraction
cfrac)))
(math-working "Fractionalize" f)
f)))
tol))))
(setq int (math-trunc aa)
aa (math-sub aa int)
cfrac (cons int cfrac))
(or (Math-zerop aa)
(setq aa (math-div 1 aa))))
cfrac)))
(defun math-eval-continued-fraction (cf)
(let ((n (car cf))
(d 1)
temp)
(while (setq cf (cdr cf))
(setq temp (math-add (math-mul (car cf) n) d)
d n
n temp))
(math-div n d)))
(defun calcFunc-fdiv (a b) ; [R I I] [Public]
(cond
((Math-num-integerp a)
(cond
((Math-num-integerp b)
(if (Math-zerop b)
(math-reject-arg a "*Division by zero")
(math-make-frac (math-trunc a) (math-trunc b))))
((eq (car-safe b) 'frac)
(if (Math-zerop (nth 1 b))
(math-reject-arg a "*Division by zero")
(math-make-frac (math-mul (math-trunc a) (nth 2 b)) (nth 1 b))))
(t (math-reject-arg b 'integerp))))
((eq (car-safe a) 'frac)
(cond
((Math-num-integerp b)
(if (Math-zerop b)
(math-reject-arg a "*Division by zero")
(math-make-frac (cadr a) (math-mul (nth 2 a) (math-trunc b)))))
((eq (car-safe b) 'frac)
(if (Math-zerop (nth 1 b))
(math-reject-arg a "*Division by zero")
(math-make-frac (math-mul (nth 1 a) (nth 2 b)) (math-mul (nth 2 a) (nth 1 b)))))
(t (math-reject-arg b 'integerp))))
(t
(math-reject-arg a 'integerp))))
(provide 'calc-frac)
;;; calc-frac.el ends here