lisp/calc/calc-frac.el

   1 ;;; calc-frac.el --- fraction functions for Calc
   2
   3 ;; Copyright (C) 1990, 1991, 1992, 1993, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
   5
   6 ;; Author: David Gillespie <daveg@synaptics.com>
   7 ;; Maintainer: Jay Belanger <jay.p.belanger@gmail.com>
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 ;; This file is autoloaded from calc-ext.el.
  29
  30 (require 'calc-ext)
  31 (require 'calc-macs)
  32
  33 (defun calc-fdiv (arg)
  34   (interactive "P")
  35   (calc-slow-wrapper
  36    (calc-binary-op ":" 'calcFunc-fdiv arg 1)))
  37
  38
  39 (defun calc-fraction (arg)
  40   (interactive "P")
  41   (calc-slow-wrapper
  42    (let ((func (if (calc-is-hyperbolic) 'calcFunc-frac 'calcFunc-pfrac)))
  43      (if (eq arg 0)
  44          (calc-enter-result 2 "frac" (list func
  45                                            (calc-top-n 2)
  46                                            (calc-top-n 1)))
  47        (calc-enter-result 1 "frac" (list func
  48                                          (calc-top-n 1)
  49                                          (prefix-numeric-value (or arg 0))))))))
  50
  51
  52 (defun calc-over-notation (fmt)
  53   (interactive "sFraction separator: ")
  54   (calc-wrapper
  55    (if (string-match "\\`\\([^ 0-9][^ 0-9]?\\)[0-9]*\\'" fmt)
  56        (let ((n nil))
  57          (if (/= (match-end 0) (match-end 1))
  58              (setq n (string-to-number (substring fmt (match-end 1)))
  59                    fmt (math-match-substring fmt 1)))
  60          (if (eq n 0) (error "Bad denominator"))
  61          (calc-change-mode 'calc-frac-format (list fmt n) t))
  62      (error "Bad fraction separator format"))))
  63
  64 (defun calc-slash-notation (n)
  65   (interactive "P")
  66   (calc-wrapper
  67    (calc-change-mode 'calc-frac-format (if n '("//" nil) '("/" nil)) t)))
  68
  69
  70 (defun calc-frac-mode (n)
  71   (interactive "P")
  72   (calc-wrapper
  73    (calc-change-mode 'calc-prefer-frac n nil t)
  74    (message (if calc-prefer-frac
  75                 "Integer division will now generate fractions"
  76               "Integer division will now generate floating-point results"))))
  77
  78
  79 ;;;; Fractions.
  80
  81 ;;; Build a normalized fraction.  [R I I]
  82 ;;; (This could probably be implemented more efficiently than using
  83 ;;;  the plain gcd algorithm.)
  84 (defun math-make-frac (num den)
  85   (if (Math-integer-negp den)
  86       (setq num (math-neg num)
  87             den (math-neg den)))
  88   (let ((gcd (math-gcd num den)))
  89     (if (eq gcd 1)
  90         (if (eq den 1)
  91             num
  92           (list 'frac num den))
  93       (if (equal gcd den)
  94           (math-quotient num gcd)
  95         (list 'frac (math-quotient num gcd) (math-quotient den gcd))))))
  96
  97 (defun calc-add-fractions (a b)
  98   (if (eq (car-safe a) 'frac)
  99       (if (eq (car-safe b) 'frac)
 100           (math-make-frac (math-add (math-mul (nth 1 a) (nth 2 b))
 101                                     (math-mul (nth 2 a) (nth 1 b)))
 102                           (math-mul (nth 2 a) (nth 2 b)))
 103         (math-make-frac (math-add (nth 1 a)
 104                                   (math-mul (nth 2 a) b))
 105                         (nth 2 a)))
 106     (math-make-frac (math-add (math-mul a (nth 2 b))
 107                               (nth 1 b))
 108                     (nth 2 b))))
 109
 110 (defun calc-mul-fractions (a b)
 111   (if (eq (car-safe a) 'frac)
 112       (if (eq (car-safe b) 'frac)
 113           (math-make-frac (math-mul (nth 1 a) (nth 1 b))
 114                           (math-mul (nth 2 a) (nth 2 b)))
 115         (math-make-frac (math-mul (nth 1 a) b)
 116                         (nth 2 a)))
 117     (math-make-frac (math-mul a (nth 1 b))
 118                     (nth 2 b))))
 119
 120 (defun calc-div-fractions (a b)
 121   (if (eq (car-safe a) 'frac)
 122       (if (eq (car-safe b) 'frac)
 123           (math-make-frac (math-mul (nth 1 a) (nth 2 b))
 124                           (math-mul (nth 2 a) (nth 1 b)))
 125         (math-make-frac (nth 1 a)
 126                         (math-mul (nth 2 a) b)))
 127     (math-make-frac (math-mul a (nth 2 b))
 128                     (nth 1 b))))
 129
 130
 131 ;;; Convert a real value to fractional form.  [T R I; T R F] [Public]
 132 (defun calcFunc-frac (a &optional tol)
 133   (or tol (setq tol 0))
 134   (cond ((Math-ratp a)
 135          a)
 136         ((memq (car a) '(cplx polar vec hms date sdev intv mod))
 137          (cons (car a) (mapcar (function
 138                                 (lambda (x)
 139                                   (calcFunc-frac x tol)))
 140                                (cdr a))))
 141         ((Math-messy-integerp a)
 142          (math-trunc a))
 143         ((Math-negp a)
 144          (math-neg (calcFunc-frac (math-neg a) tol)))
 145         ((not (eq (car a) 'float))
 146          (if (math-infinitep a)
 147              a
 148            (if (math-provably-integerp a)
 149                a
 150              (math-reject-arg a 'numberp))))
 151         ((integerp tol)
 152          (if (<= tol 0)
 153              (setq tol (+ tol calc-internal-prec)))
 154          (calcFunc-frac a (list 'float 5
 155                                 (- (+ (math-numdigs (nth 1 a))
 156                                       (nth 2 a))
 157                                    (1+ tol)))))
 158         ((not (eq (car tol) 'float))
 159          (if (Math-realp tol)
 160              (calcFunc-frac a (math-float tol))
 161            (math-reject-arg tol 'realp)))
 162         ((Math-negp tol)
 163          (calcFunc-frac a (math-neg tol)))
 164         ((Math-zerop tol)
 165          (calcFunc-frac a 0))
 166         ((not (math-lessp-float tol '(float 1 0)))
 167          (math-trunc a))
 168         ((Math-zerop a)
 169          0)
 170         (t
 171          (let ((cfrac (math-continued-fraction a tol))
 172                (calc-prefer-frac t))
 173            (math-eval-continued-fraction cfrac)))))
 174
 175 (defun math-continued-fraction (a tol)
 176   (let ((calc-internal-prec (+ calc-internal-prec 2)))
 177     (let ((cfrac nil)
 178           (aa a)
 179           (calc-prefer-frac nil)
 180           int)
 181       (while (or (null cfrac)
 182                  (and (not (Math-zerop aa))
 183                       (not (math-lessp-float
 184                             (math-abs
 185                              (math-sub a
 186                                        (let ((f (math-eval-continued-fraction
 187                                                  cfrac)))
 188                                          (math-working "Fractionalize" f)
 189                                          f)))
 190                             tol))))
 191         (setq int (math-trunc aa)
 192               aa (math-sub aa int)
 193               cfrac (cons int cfrac))
 194         (or (Math-zerop aa)
 195             (setq aa (math-div 1 aa))))
 196       cfrac)))
 197
 198 (defun math-eval-continued-fraction (cf)
 199   (let ((n (car cf))
 200         (d 1)
 201         temp)
 202     (while (setq cf (cdr cf))
 203       (setq temp (math-add (math-mul (car cf) n) d)
 204             d n
 205             n temp))
 206     (math-div n d)))
 207
 208
 209
 210 (defun calcFunc-fdiv (a b)   ; [R I I] [Public]
 211   (if (Math-num-integerp a)
 212       (if (Math-num-integerp b)
 213           (if (Math-zerop b)
 214               (math-reject-arg a "*Division by zero")
 215             (math-make-frac (math-trunc a) (math-trunc b)))
 216         (math-reject-arg b 'integerp))
 217     (math-reject-arg a 'integerp)))
 218
 219 (provide 'calc-frac)
 220
 221 ;; arch-tag: 89d65274-0b3b-42d8-aacd-eaf86da5b4ea
 222 ;;; calc-frac.el ends here