diff options
| author | Stefan Monnier | 2008-06-03 08:08:01 +0000 |
|---|---|---|
| committer | Stefan Monnier | 2008-06-03 08:08:01 +0000 |
| commit | a87c1daf657350ebae2cc9935d10dacde0b6f00a (patch) | |
| tree | 1c59290a7291fa76725a15e5b57401adb5e5193f /lisp/obsolete/float.el | |
| parent | 8d27bcdf2e758dc6a4868c8fdee65b9a93101b67 (diff) | |
| download | emacs-a87c1daf657350ebae2cc9935d10dacde0b6f00a.tar.gz emacs-a87c1daf657350ebae2cc9935d10dacde0b6f00a.zip | |
* obsolete/bg-mouse.el, obsolete/float.el, obsolete/hilit19.el,
* obsolete/lselect.el, obsolete/mlsupport.el, obsolete/ooutline.el,
* obsolete/profile.el, obsolete/rsz-mini.el, obsolete/uncompress.el,
* obsolete/auto-show.el, obsolete/hscroll.el:
Remove packages that were obsolete in Emacs-20, or that were obsolete
in Emacs-21 and do not contain any more code.
Diffstat (limited to 'lisp/obsolete/float.el')
| -rw-r--r-- | lisp/obsolete/float.el | 460 |
1 files changed, 0 insertions, 460 deletions
diff --git a/lisp/obsolete/float.el b/lisp/obsolete/float.el deleted file mode 100644 index e86b8633f45..00000000000 --- a/lisp/obsolete/float.el +++ /dev/null | |||
| @@ -1,460 +0,0 @@ | |||
| 1 | ;;; float.el --- obsolete floating point arithmetic package | ||
| 2 | |||
| 3 | ;; Copyright (C) 1986, 2001, 2002, 2003, 2004, 2005, | ||
| 4 | ;; 2006, 2007, 2008 Free Software Foundation, Inc. | ||
| 5 | |||
| 6 | ;; Author: Bill Rosenblatt | ||
| 7 | ;; Maintainer: FSF | ||
| 8 | ;; Keywords: extensions | ||
| 9 | |||
| 10 | ;; This file is part of GNU Emacs. | ||
| 11 | |||
| 12 | ;; GNU Emacs is free software: you can redistribute it and/or modify | ||
| 13 | ;; it under the terms of the GNU General Public License as published by | ||
| 14 | ;; the Free Software Foundation, either version 3 of the License, or | ||
| 15 | ;; (at your option) any later version. | ||
| 16 | |||
| 17 | ;; GNU Emacs is distributed in the hope that it will be useful, | ||
| 18 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 19 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| 20 | ;; GNU General Public License for more details. | ||
| 21 | |||
| 22 | ;; You should have received a copy of the GNU General Public License | ||
| 23 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. | ||
| 24 | |||
| 25 | ;;; Commentary: | ||
| 26 | |||
| 27 | ;; This file has been obsolete since Emacs 22.1. | ||
| 28 | |||
| 29 | ;; Floating point numbers are represented by dot-pairs (mant . exp) | ||
| 30 | ;; where mant is the 24-bit signed integral mantissa and exp is the | ||
| 31 | ;; base 2 exponent. | ||
| 32 | ;; | ||
| 33 | ;; Emacs LISP supports a 24-bit signed integer data type, which has a | ||
| 34 | ;; range of -(2**23) to +(2**23)-1, or -8388608 to 8388607 decimal. | ||
| 35 | ;; This gives six significant decimal digit accuracy. Exponents can | ||
| 36 | ;; be anything in the range -(2**23) to +(2**23)-1. | ||
| 37 | ;; | ||
| 38 | ;; User interface: | ||
| 39 | ;; function f converts from integer to floating point | ||
| 40 | ;; function string-to-float converts from string to floating point | ||
| 41 | ;; function fint converts a floating point to integer (with truncation) | ||
| 42 | ;; function float-to-string converts from floating point to string | ||
| 43 | ;; | ||
| 44 | ;; Caveats: | ||
| 45 | ;; - Exponents outside of the range of +/-100 or so will cause certain | ||
| 46 | ;; functions (especially conversion routines) to take forever. | ||
| 47 | ;; - Very little checking is done for fixed point overflow/underflow. | ||
| 48 | ;; - No checking is done for over/underflow of the exponent | ||
| 49 | ;; (hardly necessary when exponent can be 2**23). | ||
| 50 | ;; | ||
| 51 | ;; | ||
| 52 | ;; Bill Rosenblatt | ||
| 53 | ;; June 20, 1986 | ||
| 54 | ;; | ||
| 55 | |||
| 56 | ;;; Code: | ||
| 57 | |||
| 58 | ;; fundamental implementation constants | ||
| 59 | (defconst exp-base 2 | ||
| 60 | "Base of exponent in this floating point representation.") | ||
| 61 | |||
| 62 | (defconst mantissa-bits 24 | ||
| 63 | "Number of significant bits in this floating point representation.") | ||
| 64 | |||
| 65 | (defconst decimal-digits 6 | ||
| 66 | "Number of decimal digits expected to be accurate.") | ||
| 67 | |||
| 68 | (defconst expt-digits 2 | ||
| 69 | "Maximum permitted digits in a scientific notation exponent.") | ||
| 70 | |||
| 71 | ;; other constants | ||
| 72 | (defconst maxbit (1- mantissa-bits) | ||
| 73 | "Number of highest bit") | ||
| 74 | |||
| 75 | (defconst mantissa-maxval (1- (ash 1 maxbit)) | ||
| 76 | "Maximum permissible value of mantissa") | ||
| 77 | |||
| 78 | (defconst mantissa-minval (ash 1 maxbit) | ||
| 79 | "Minimum permissible value of mantissa") | ||
| 80 | |||
| 81 | (defconst floating-point-regexp | ||
| 82 | "^[ \t]*\\(-?\\)\\([0-9]*\\)\ | ||
| 83 | \\(\\.\\([0-9]*\\)\\|\\)\ | ||
| 84 | \\(\\(\\([Ee]\\)\\(-?\\)\\([0-9][0-9]*\\)\\)\\|\\)[ \t]*$" | ||
| 85 | "Regular expression to match floating point numbers. Extract matches: | ||
| 86 | 1 - minus sign | ||
| 87 | 2 - integer part | ||
| 88 | 4 - fractional part | ||
| 89 | 8 - minus sign for power of ten | ||
| 90 | 9 - power of ten | ||
| 91 | ") | ||
| 92 | |||
| 93 | (defconst high-bit-mask (ash 1 maxbit) | ||
| 94 | "Masks all bits except the high-order (sign) bit.") | ||
| 95 | |||
| 96 | (defconst second-bit-mask (ash 1 (1- maxbit)) | ||
| 97 | "Masks all bits except the highest-order magnitude bit") | ||
| 98 | |||
| 99 | ;; various useful floating point constants | ||
| 100 | (defconst _f0 '(0 . 1)) | ||
| 101 | |||
| 102 | (defconst _f1/2 '(4194304 . -23)) | ||
| 103 | |||
| 104 | (defconst _f1 '(4194304 . -22)) | ||
| 105 | |||
| 106 | (defconst _f10 '(5242880 . -19)) | ||
| 107 | |||
| 108 | ;; support for decimal conversion routines | ||
| 109 | (defvar powers-of-10 (make-vector (1+ decimal-digits) _f1)) | ||
| 110 | (aset powers-of-10 1 _f10) | ||
| 111 | (aset powers-of-10 2 '(6553600 . -16)) | ||
| 112 | (aset powers-of-10 3 '(8192000 . -13)) | ||
| 113 | (aset powers-of-10 4 '(5120000 . -9)) | ||
| 114 | (aset powers-of-10 5 '(6400000 . -6)) | ||
| 115 | (aset powers-of-10 6 '(8000000 . -3)) | ||
| 116 | |||
| 117 | (defconst all-decimal-digs-minval (aref powers-of-10 (1- decimal-digits))) | ||
| 118 | (defconst highest-power-of-10 (aref powers-of-10 decimal-digits)) | ||
| 119 | |||
| 120 | (defun fashl (fnum) ; floating-point arithmetic shift left | ||
| 121 | (cons (ash (car fnum) 1) (1- (cdr fnum)))) | ||
| 122 | |||
| 123 | (defun fashr (fnum) ; floating point arithmetic shift right | ||
| 124 | (cons (ash (car fnum) -1) (1+ (cdr fnum)))) | ||
| 125 | |||
| 126 | (defun normalize (fnum) | ||
| 127 | (if (> (car fnum) 0) ; make sure next-to-highest bit is set | ||
| 128 | (while (zerop (logand (car fnum) second-bit-mask)) | ||
| 129 | (setq fnum (fashl fnum))) | ||
| 130 | (if (< (car fnum) 0) ; make sure highest bit is set | ||
| 131 | (while (zerop (logand (car fnum) high-bit-mask)) | ||
| 132 | (setq fnum (fashl fnum))) | ||
| 133 | (setq fnum _f0))) ; "standard 0" | ||
| 134 | fnum) | ||
| 135 | |||
| 136 | (defun abs (n) ; integer absolute value | ||
| 137 | (if (>= n 0) n (- n))) | ||
| 138 | |||
| 139 | (defun fabs (fnum) ; re-normalize after taking abs value | ||
| 140 | (normalize (cons (abs (car fnum)) (cdr fnum)))) | ||
| 141 | |||
| 142 | (defun xor (a b) ; logical exclusive or | ||
| 143 | (and (or a b) (not (and a b)))) | ||
| 144 | |||
| 145 | (defun same-sign (a b) ; two f-p numbers have same sign? | ||
| 146 | (not (xor (natnump (car a)) (natnump (car b))))) | ||
| 147 | |||
| 148 | (defun extract-match (str i) ; used after string-match | ||
| 149 | (condition-case () | ||
| 150 | (substring str (match-beginning i) (match-end i)) | ||
| 151 | (error ""))) | ||
| 152 | |||
| 153 | ;; support for the multiplication function | ||
| 154 | (defconst halfword-bits (/ mantissa-bits 2)) ; bits in a halfword | ||
| 155 | (defconst masklo (1- (ash 1 halfword-bits))) ; isolate the lower halfword | ||
| 156 | (defconst maskhi (lognot masklo)) ; isolate the upper halfword | ||
| 157 | (defconst round-limit (ash 1 (/ halfword-bits 2))) | ||
| 158 | |||
| 159 | (defun hihalf (n) ; return high halfword, shifted down | ||
| 160 | (ash (logand n maskhi) (- halfword-bits))) | ||
| 161 | |||
| 162 | (defun lohalf (n) ; return low halfword | ||
| 163 | (logand n masklo)) | ||
| 164 | |||
| 165 | ;; Visible functions | ||
| 166 | |||
| 167 | ;; Arithmetic functions | ||
| 168 | (defun f+ (a1 a2) | ||
| 169 | "Returns the sum of two floating point numbers." | ||
| 170 | (let ((f1 (fmax a1 a2)) | ||
| 171 | (f2 (fmin a1 a2))) | ||
| 172 | (if (same-sign a1 a2) | ||
| 173 | (setq f1 (fashr f1) ; shift right to avoid overflow | ||
| 174 | f2 (fashr f2))) | ||
| 175 | (normalize | ||
| 176 | (cons (+ (car f1) (ash (car f2) (- (cdr f2) (cdr f1)))) | ||
| 177 | (cdr f1))))) | ||
| 178 | |||
| 179 | (defun f- (a1 &optional a2) ; unary or binary minus | ||
| 180 | "Returns the difference of two floating point numbers." | ||
| 181 | (if a2 | ||
| 182 | (f+ a1 (f- a2)) | ||
| 183 | (normalize (cons (- (car a1)) (cdr a1))))) | ||
| 184 | |||
| 185 | (defun f* (a1 a2) ; multiply in halfword chunks | ||
| 186 | "Returns the product of two floating point numbers." | ||
| 187 | (let* ((i1 (car (fabs a1))) | ||
| 188 | (i2 (car (fabs a2))) | ||
| 189 | (sign (not (same-sign a1 a2))) | ||
| 190 | (prodlo (+ (hihalf (* (lohalf i1) (lohalf i2))) | ||
| 191 | (lohalf (* (hihalf i1) (lohalf i2))) | ||
| 192 | (lohalf (* (lohalf i1) (hihalf i2))))) | ||
| 193 | (prodhi (+ (* (hihalf i1) (hihalf i2)) | ||
| 194 | (hihalf (* (hihalf i1) (lohalf i2))) | ||
| 195 | (hihalf (* (lohalf i1) (hihalf i2))) | ||
| 196 | (hihalf prodlo)))) | ||
| 197 | (if (> (lohalf prodlo) round-limit) | ||
| 198 | (setq prodhi (1+ prodhi))) ; round off truncated bits | ||
| 199 | (normalize | ||
| 200 | (cons (if sign (- prodhi) prodhi) | ||
| 201 | (+ (cdr (fabs a1)) (cdr (fabs a2)) mantissa-bits))))) | ||
| 202 | |||
| 203 | (defun f/ (a1 a2) ; SLOW subtract-and-shift algorithm | ||
| 204 | "Returns the quotient of two floating point numbers." | ||
| 205 | (if (zerop (car a2)) ; if divide by 0 | ||
| 206 | (signal 'arith-error (list "attempt to divide by zero" a1 a2)) | ||
| 207 | (let ((bits (1- maxbit)) | ||
| 208 | (quotient 0) | ||
| 209 | (dividend (car (fabs a1))) | ||
| 210 | (divisor (car (fabs a2))) | ||
| 211 | (sign (not (same-sign a1 a2)))) | ||
| 212 | (while (natnump bits) | ||
| 213 | (if (< (- dividend divisor) 0) | ||
| 214 | (setq quotient (ash quotient 1)) | ||
| 215 | (setq quotient (1+ (ash quotient 1)) | ||
| 216 | dividend (- dividend divisor))) | ||
| 217 | (setq dividend (ash dividend 1) | ||
| 218 | bits (1- bits))) | ||
| 219 | (normalize | ||
| 220 | (cons (if sign (- quotient) quotient) | ||
| 221 | (- (cdr (fabs a1)) (cdr (fabs a2)) (1- maxbit))))))) | ||
| 222 | |||
| 223 | (defun f% (a1 a2) | ||
| 224 | "Returns the remainder of first floating point number divided by second." | ||
| 225 | (f- a1 (f* (ftrunc (f/ a1 a2)) a2))) | ||
| 226 | |||
| 227 | |||
| 228 | ;; Comparison functions | ||
| 229 | (defun f= (a1 a2) | ||
| 230 | "Returns t if two floating point numbers are equal, nil otherwise." | ||
| 231 | (equal a1 a2)) | ||
| 232 | |||
| 233 | (defun f> (a1 a2) | ||
| 234 | "Returns t if first floating point number is greater than second, | ||
| 235 | nil otherwise." | ||
| 236 | (cond ((and (natnump (car a1)) (< (car a2) 0)) | ||
| 237 | t) ; a1 nonnegative, a2 negative | ||
| 238 | ((and (> (car a1) 0) (<= (car a2) 0)) | ||
| 239 | t) ; a1 positive, a2 nonpositive | ||
| 240 | ((and (<= (car a1) 0) (natnump (car a2))) | ||
| 241 | nil) ; a1 nonpos, a2 nonneg | ||
| 242 | ((/= (cdr a1) (cdr a2)) ; same signs. exponents differ | ||
| 243 | (> (cdr a1) (cdr a2))) ; compare the mantissas. | ||
| 244 | (t | ||
| 245 | (> (car a1) (car a2))))) ; same exponents. | ||
| 246 | |||
| 247 | (defun f>= (a1 a2) | ||
| 248 | "Returns t if first floating point number is greater than or equal to | ||
| 249 | second, nil otherwise." | ||
| 250 | (or (f> a1 a2) (f= a1 a2))) | ||
| 251 | |||
| 252 | (defun f< (a1 a2) | ||
| 253 | "Returns t if first floating point number is less than second, | ||
| 254 | nil otherwise." | ||
| 255 | (not (f>= a1 a2))) | ||
| 256 | |||
| 257 | (defun f<= (a1 a2) | ||
| 258 | "Returns t if first floating point number is less than or equal to | ||
| 259 | second, nil otherwise." | ||
| 260 | (not (f> a1 a2))) | ||
| 261 | |||
| 262 | (defun f/= (a1 a2) | ||
| 263 | "Returns t if first floating point number is not equal to second, | ||
| 264 | nil otherwise." | ||
| 265 | (not (f= a1 a2))) | ||
| 266 | |||
| 267 | (defun fmin (a1 a2) | ||
| 268 | "Returns the minimum of two floating point numbers." | ||
| 269 | (if (f< a1 a2) a1 a2)) | ||
| 270 | |||
| 271 | (defun fmax (a1 a2) | ||
| 272 | "Returns the maximum of two floating point numbers." | ||
| 273 | (if (f> a1 a2) a1 a2)) | ||
| 274 | |||
| 275 | (defun fzerop (fnum) | ||
| 276 | "Returns t if the floating point number is zero, nil otherwise." | ||
| 277 | (= (car fnum) 0)) | ||
| 278 | |||
| 279 | (defun floatp (fnum) | ||
| 280 | "Returns t if the arg is a floating point number, nil otherwise." | ||
| 281 | (and (consp fnum) (integerp (car fnum)) (integerp (cdr fnum)))) | ||
| 282 | |||
| 283 | ;; Conversion routines | ||
| 284 | (defun f (int) | ||
| 285 | "Convert the integer argument to floating point, like a C cast operator." | ||
| 286 | (normalize (cons int '0))) | ||
| 287 | |||
| 288 | (defun int-to-hex-string (int) | ||
| 289 | "Convert the integer argument to a C-style hexadecimal string." | ||
| 290 | (let ((shiftval -20) | ||
| 291 | (str "0x") | ||
| 292 | (hex-chars "0123456789ABCDEF")) | ||
| 293 | (while (<= shiftval 0) | ||
| 294 | (setq str (concat str (char-to-string | ||
| 295 | (aref hex-chars | ||
| 296 | (logand (lsh int shiftval) 15)))) | ||
| 297 | shiftval (+ shiftval 4))) | ||
| 298 | str)) | ||
| 299 | |||
| 300 | (defun ftrunc (fnum) ; truncate fractional part | ||
| 301 | "Truncate the fractional part of a floating point number." | ||
| 302 | (cond ((natnump (cdr fnum)) ; it's all integer, return number as is | ||
| 303 | fnum) | ||
| 304 | ((<= (cdr fnum) (- maxbit)) ; it's all fractional, return 0 | ||
| 305 | '(0 . 1)) | ||
| 306 | (t ; otherwise mask out fractional bits | ||
| 307 | (let ((mant (car fnum)) (exp (cdr fnum))) | ||
| 308 | (normalize | ||
| 309 | (cons (if (natnump mant) ; if negative, use absolute value | ||
| 310 | (ash (ash mant exp) (- exp)) | ||
| 311 | (- (ash (ash (- mant) exp) (- exp)))) | ||
| 312 | exp)))))) | ||
| 313 | |||
| 314 | (defun fint (fnum) ; truncate and convert to integer | ||
| 315 | "Convert the floating point number to integer, with truncation, | ||
| 316 | like a C cast operator." | ||
| 317 | (let* ((tf (ftrunc fnum)) (tint (car tf)) (texp (cdr tf))) | ||
| 318 | (cond ((>= texp mantissa-bits) ; too high, return "maxint" | ||
| 319 | mantissa-maxval) | ||
| 320 | ((<= texp (- mantissa-bits)) ; too low, return "minint" | ||
| 321 | mantissa-minval) | ||
| 322 | (t ; in range | ||
| 323 | (ash tint texp))))) ; shift so that exponent is 0 | ||
| 324 | |||
| 325 | (defun float-to-string (fnum &optional sci) | ||
| 326 | "Convert the floating point number to a decimal string. | ||
| 327 | Optional second argument non-nil means use scientific notation." | ||
| 328 | (let* ((value (fabs fnum)) (sign (< (car fnum) 0)) | ||
| 329 | (power 0) (result 0) (str "") | ||
| 330 | (temp 0) (pow10 _f1)) | ||
| 331 | |||
| 332 | (if (f= fnum _f0) | ||
| 333 | "0" | ||
| 334 | (if (f>= value _f1) ; find largest power of 10 <= value | ||
| 335 | (progn ; value >= 1, power is positive | ||
| 336 | (while (f<= (setq temp (f* pow10 highest-power-of-10)) value) | ||
| 337 | (setq pow10 temp | ||
| 338 | power (+ power decimal-digits))) | ||
| 339 | (while (f<= (setq temp (f* pow10 _f10)) value) | ||
| 340 | (setq pow10 temp | ||
| 341 | power (1+ power)))) | ||
| 342 | (progn ; value < 1, power is negative | ||
| 343 | (while (f> (setq temp (f/ pow10 highest-power-of-10)) value) | ||
| 344 | (setq pow10 temp | ||
| 345 | power (- power decimal-digits))) | ||
| 346 | (while (f> pow10 value) | ||
| 347 | (setq pow10 (f/ pow10 _f10) | ||
| 348 | power (1- power))))) | ||
| 349 | ; get value in range 100000 to 999999 | ||
| 350 | (setq value (f* (f/ value pow10) all-decimal-digs-minval) | ||
| 351 | result (ftrunc value)) | ||
| 352 | (let (int) | ||
| 353 | (if (f> (f- value result) _f1/2) ; round up if remainder > 0.5 | ||
| 354 | (setq int (1+ (fint result))) | ||
| 355 | (setq int (fint result))) | ||
| 356 | (setq str (int-to-string int)) | ||
| 357 | (if (>= int 1000000) | ||
| 358 | (setq power (1+ power)))) | ||
| 359 | |||
| 360 | (if sci ; scientific notation | ||
| 361 | (setq str (concat (substring str 0 1) "." (substring str 1) | ||
| 362 | "E" (int-to-string power))) | ||
| 363 | |||
| 364 | ; regular decimal string | ||
| 365 | (cond ((>= power (1- decimal-digits)) | ||
| 366 | ; large power, append zeroes | ||
| 367 | (let ((zeroes (- power decimal-digits))) | ||
| 368 | (while (natnump zeroes) | ||
| 369 | (setq str (concat str "0") | ||
| 370 | zeroes (1- zeroes))))) | ||
| 371 | |||
| 372 | ; negative power, prepend decimal | ||
| 373 | ((< power 0) ; point and zeroes | ||
| 374 | (let ((zeroes (- (- power) 2))) | ||
| 375 | (while (natnump zeroes) | ||
| 376 | (setq str (concat "0" str) | ||
| 377 | zeroes (1- zeroes))) | ||
| 378 | (setq str (concat "0." str)))) | ||
| 379 | |||
| 380 | (t ; in range, insert decimal point | ||
| 381 | (setq str (concat | ||
| 382 | (substring str 0 (1+ power)) | ||
| 383 | "." | ||
| 384 | (substring str (1+ power))))))) | ||
| 385 | |||
| 386 | (if sign ; if negative, prepend minus sign | ||
| 387 | (concat "-" str) | ||
| 388 | str)))) | ||
| 389 | |||
| 390 | |||
| 391 | ;; string to float conversion. | ||
| 392 | ;; accepts scientific notation, but ignores anything after the first two | ||
| 393 | ;; digits of the exponent. | ||
| 394 | (defun string-to-float (str) | ||
| 395 | "Convert the string to a floating point number. | ||
| 396 | Accepts a decimal string in scientific notation, with exponent preceded | ||
| 397 | by either E or e. Only the six most significant digits of the integer | ||
| 398 | and fractional parts are used; only the first two digits of the exponent | ||
| 399 | are used. Negative signs preceding both the decimal number and the exponent | ||
| 400 | are recognized." | ||
| 401 | |||
| 402 | (if (string-match floating-point-regexp str 0) | ||
| 403 | (let (power) | ||
| 404 | (f* | ||
| 405 | ; calculate the mantissa | ||
| 406 | (let* ((int-subst (extract-match str 2)) | ||
| 407 | (fract-subst (extract-match str 4)) | ||
| 408 | (digit-string (concat int-subst fract-subst)) | ||
| 409 | (mant-sign (equal (extract-match str 1) "-")) | ||
| 410 | (leading-0s 0) (round-up nil)) | ||
| 411 | |||
| 412 | ; get rid of leading 0's | ||
| 413 | (setq power (- (length int-subst) decimal-digits)) | ||
| 414 | (while (and (< leading-0s (length digit-string)) | ||
| 415 | (= (aref digit-string leading-0s) ?0)) | ||
| 416 | (setq leading-0s (1+ leading-0s))) | ||
| 417 | (setq power (- power leading-0s) | ||
| 418 | digit-string (substring digit-string leading-0s)) | ||
| 419 | |||
| 420 | ; if more than 6 digits, round off | ||
| 421 | (if (> (length digit-string) decimal-digits) | ||
| 422 | (setq round-up (>= (aref digit-string decimal-digits) ?5) | ||
| 423 | digit-string (substring digit-string 0 decimal-digits)) | ||
| 424 | (setq power (+ power (- decimal-digits (length digit-string))))) | ||
| 425 | |||
| 426 | ; round up and add minus sign, if necessary | ||
| 427 | (f (* (+ (string-to-number digit-string) | ||
| 428 | (if round-up 1 0)) | ||
| 429 | (if mant-sign -1 1)))) | ||
| 430 | |||
| 431 | ; calculate the exponent (power of ten) | ||
| 432 | (let* ((expt-subst (extract-match str 9)) | ||
| 433 | (expt-sign (equal (extract-match str 8) "-")) | ||
| 434 | (expt 0) (chunks 0) (tens 0) (exponent _f1) | ||
| 435 | (func 'f*)) | ||
| 436 | |||
| 437 | (setq expt (+ (* (string-to-number | ||
| 438 | (substring expt-subst 0 | ||
| 439 | (min expt-digits (length expt-subst)))) | ||
| 440 | (if expt-sign -1 1)) | ||
| 441 | power)) | ||
| 442 | (if (< expt 0) ; if power of 10 negative | ||
| 443 | (setq expt (- expt) ; take abs val of exponent | ||
| 444 | func 'f/)) ; and set up to divide, not multiply | ||
| 445 | |||
| 446 | (setq chunks (/ expt decimal-digits) | ||
| 447 | tens (% expt decimal-digits)) | ||
| 448 | ; divide or multiply by "chunks" of 10**6 | ||
| 449 | (while (> chunks 0) | ||
| 450 | (setq exponent (funcall func exponent highest-power-of-10) | ||
| 451 | chunks (1- chunks))) | ||
| 452 | ; divide or multiply by remaining power of ten | ||
| 453 | (funcall func exponent (aref powers-of-10 tens))))) | ||
| 454 | |||
| 455 | _f0)) ; if invalid, return 0 | ||
| 456 | |||
| 457 | (provide 'float) | ||
| 458 | |||
| 459 | ;; arch-tag: cc0c89c6-5718-49af-978e-585f6b14e347 | ||
| 460 | ;;; float.el ends here | ||