src/nisimp.lisp

   1 ;;; -*-  Mode: Lisp; Package: Maxima; Syntax: Common-Lisp; Base: 10 -*- ;;;;
   2 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   3 ;;;     The data in this file contains enhancments.                    ;;;;;
   4 ;;;                                                                    ;;;;;
   5 ;;;  Copyright (c) 1984,1987 by William Schelter,University of Texas   ;;;;;
   6 ;;;     All rights reserved                                            ;;;;;
   7 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   8 ;;;     (c) Copyright 1982 Massachusetts Institute of Technology         ;;;
   9 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  10
  11 (in-package :maxima)
  12
  13 (macsyma-module nisimp)
  14
  15 ;;;programs for the LET LETSIMP LETRULES and REMLET commands
  16 ;;;these programs use the names LETSIMPTREE and LETRULES on the
  17 ;;;property list of atoms
  18 ;;;except for the top level programs all program names have the prefix NIS
  19
  20 (declare-top (special nistree nisrules nisflag $ratexpand varlist $ratfac))
  21
  22 (defmvar $letvarsimp nil)
  23
  24 (defmvar $letrat nil)
  25
  26 (defmvar $default_let_rule_package '$default_let_rule_package
  27   "The name of the default rule package used by `let' and `letsimp'")
  28
  29 (putprop '$default_let_rule_package 'let-rule-setter 'assign)
  30
  31 (defmvar $current_let_rule_package '$default_let_rule_package
  32   "The name of the current rule package used by `let' and `letsimp'")
  33
  34 (putprop '$current_let_rule_package 'let-rule-setter 'assign)
  35
  36 (defmvar $let_rule_packages '((mlist) $default_let_rule_package)
  37   "The names of the various let rule simplification packages")
  38
  39 (putprop '$let_rule_packages 'let-rule-setter 'assign)
  40
  41 (setq nisrules nil nistree nil)
  42
  43 (defun let-rule-setter (var val)
  44   (cond ((eq var '$default_let_rule_package)
  45          (merror (intl:gettext "assignment: cannot assign to default_let_rule_package.")))
  46         ((and (eq var '$current_let_rule_package)
  47               (not (memalike val (cdr $let_rule_packages))))
  48          (merror (intl:gettext "assignment: ~M is not a rule package.") val))
  49         ((eq var '$let_rule_packages)
  50          (merror (intl:gettext "assignment: cannot assign to let_rule_packages.~%assignment: call 'let' to create let rule packages.")))))
  51
  52 (defmspec $let (l) (setq l (cdr l))
  53           (if (null (cdr l)) (wna-err '$let))
  54           ;;LET([PATTERN,REPL,PRED,ARG1,...,ARGN],NAME)
  55           (prog (pattern pat replacement treename text $ratfac)
  56              ;;LET(PATTERN,REPL,PRED,ARG1,...,ARGN)
  57              (cond ((atom (car l))
  58                     (setq treename $current_let_rule_package))
  59                    ((eq 'mlist (caaar l))
  60                     (setq treename (cadr l))
  61                     (if (not (symbolp treename))
  62                         (improper-arg-err treename '$let))
  63                     (setq l (cdar l)))
  64                    (t (setq treename $current_let_rule_package)))
  65              (let ((nistree (mget treename 'letsimptree))
  66                    (nisrules (mget treename 'letrules)))
  67                (setq pat (strip-lineinfo (meval (car l))))
  68                (setq replacement (cdr l))
  69                (setq pattern (cond ((atom pat) (list pat))
  70                                    ((eq (caar pat) 'mtimes)
  71                                     (cdr pat))
  72                                    (t (list pat))))
  73                (setq nistree (nislet nistree pattern replacement))
  74                (cond (treename (mputprop treename
  75                                          nistree
  76                                          'letsimptree)
  77                                (add2lnc treename $let_rule_packages)))
  78                (nonsymchk (caddr l) '$let)
  79                (setq text
  80                      (append (list '(mtext) pat '| --> | )
  81                              (cond ((cddr l)
  82                                     (list (cadr l)
  83                                           '#.(intern (format nil " ~A " 'where))
  84                                           (cons (list (caddr l))
  85                                                 (cdddr l))))
  86                                    (t replacement))))
  87                (setq nisrules (append (list text) nisrules))
  88                (cond (treename (mputprop treename
  89                                          nisrules
  90                                          'letrules)))
  91                (return text))))
  92
  93 (defun nislet (tree list function)
  94   (prog (permlist)
  95      (setq permlist (nispermutations list))
  96      step (cond ((eq nil permlist) (return tree)))
  97      (setq tree (nistreebuilder tree (car permlist) function))
  98      (setq permlist (cdr permlist))
  99      (go step)))
 100
 101 (defun nispermutations (llist)
 102   (cond
 103     ((null (cdr llist)) (list llist))
 104     (t
 105      (prog (permlist a)
 106       step (setq permlist
 107                  (append
 108                   (nisaddon (car llist)
 109                             (nispermutations (append a (cdr llist))))
 110                   permlist))
 111       (if (null (cdr llist)) (return permlist))
 112       (push (car llist) a)
 113       (setq llist (cdr llist))
 114       (go step)))))
 115
 116 (defun nisaddon (x llist)
 117   (if llist (cons (cons x (car llist)) (nisaddon x (cdr llist)))))
 118
 119 (defun nistreebuilder (tree perm function)
 120   (cond ((null perm) (cons (list function) tree))
 121         ((null tree)
 122          (list (cons (car perm)
 123                      (nistreebuilder nil (cdr perm) function))))
 124         ((equal (car perm) (caar tree))
 125          (nisswcar tree
 126                    (nisswcdr (car tree)
 127                              (nistreebuilder (cdar tree)
 128                                              (cdr perm)
 129                                              function))))
 130         (t (nisswcdr tree
 131                      (nistreebuilder (cdr tree)
 132                                      perm
 133                                      function)))))
 134
 135 (defun nisswcar (x y)
 136   (cons y (cdr x)))
 137
 138 (defun nisswcdr (x y)
 139   (cons (car x) y))
 140
 141 (defmspec $remlet (x)
 142   (setq x (cdr x))
 143   ;; REMLET(PROD,NAME) REMLET(PROD) REMLET() REMLET(FALSE,NAME)
 144   (prog (pattern text treename)
 145      (cond ((cddr x) (wna-err '$remlet))
 146            ((null (cdr x)) (setq treename $current_let_rule_package))
 147            (t (setq treename (cadr x))
 148               (if (not (symbolp treename))
 149                   (improper-arg-err treename '$remlet))))
 150      (setq pattern (strip-lineinfo (meval (car x))))
 151      (when (or (not pattern) (eq '$all pattern))
 152        (setq nisrules nil nistree nil)
 153        (unless (eq treename '$default_let_rule_package)
 154          (setq $let_rule_packages (delete treename $let_rule_packages :count 1 :test #'eq)))
 155        (go a))
 156      (setq nistree (mget treename 'letsimptree))
 157      (if (setq text (nisremlet pattern)) (return text))
 158      (if nistree
 159          (setq nisrules
 160                (nistreelister (mget treename 'letrules) pattern))
 161          (setq nisrules nil))
 162      a    (mputprop treename nistree 'letsimptree)
 163      (mputprop treename nisrules 'letrules)
 164      (return '$done)))
 165
 166 (defun nistreelister (llist pattern)
 167   (prog (x)
 168    a    (if (alike1 pattern (cadar llist)) (return (append x (cdr llist))))
 169    (setq x (append x (list (car llist))) llist (cdr llist))
 170    (go a)))
 171
 172 (defun nisremlet (pat)
 173   (prog (llist permlist x)
 174      (setq llist (if (mtimesp pat) (cdr pat) (ncons pat)))
 175      (setq nisflag t x nistree)
 176      (setq permlist (nispermutations llist))
 177      step (when (null permlist) (setq nistree x) (return nil))
 178      (setq x (nistreetrimmer (car permlist) x))
 179      (if (null nisflag) (merror (intl:gettext "remlet: no rule found: ~M") pat))
 180      (setq permlist (cdr permlist))
 181      (go step)))
 182
 183 (defun nistreetrimmer (perm tree)
 184   (cond ((null perm)
 185          (cond ((null tree) (setq nisflag nil))
 186                ((null (cdar tree))
 187                 (setq nisflag (caar tree)) (cdr tree))
 188                (t (nisswcdr tree (nistreetrimmer nil (cdr tree))))))
 189         ((null tree) (setq nisflag nil))
 190         ((equal (car perm) (caar tree))
 191          (prog (x)
 192             (setq x (nistreetrimmer (cdr perm) (cdar tree)))
 193             (if (null x) (return (cdr tree)))
 194             (return (nisswcar tree (nisswcdr (car tree) x)))))
 195         (t (nisswcdr tree (nistreetrimmer perm (cdr tree))))))
 196
 197 (defmspec $letrules (name)
 198   (setq name (cdr name))                ;LETRULES(NAME)
 199   (let ((treename (if name (car name) $current_let_rule_package)))
 200     (if (not (symbolp treename)) (improper-arg-err treename '$letrules))
 201     (setq nistree (mget treename 'letsimptree)
 202           nisrules (mget treename 'letrules))
 203     (apply #'$disp nisrules)))
 204
 205 (defmspec $letsimp (form)               ;letsimp(expr,tree1,...,treen)
 206   (setq form (cdr form))
 207   (let* ((expr (strip-lineinfo (meval (pop form))))
 208          (sw ($ratp expr))
 209          $ratfac)
 210     (progv (unless sw '(varlist genvar))
 211         (unless sw (list varlist genvar))
 212       (when (and sw (member 'trunc (cdar expr) :test #'eq))
 213         (setq expr ($taytorat expr)))
 214       (dolist (rulepackage (or form (list $current_let_rule_package))
 215                (if sw (ratf expr) expr))
 216         (unless (symbolp rulepackage)
 217           (improper-arg-err rulepackage '$letsimp))
 218         (when (setq nistree (mget rulepackage 'letsimptree))
 219           ;; Whereas nisletsimp returns an expression in general
 220           ;; representation, the original expr might be in CRE form.
 221           ;; Regardless, we use ratf to make sure varlist and genvar
 222           ;; know of expr's kernels.
 223           (setq expr (nisletsimp (if (atom expr)
 224                                      expr
 225                                      (ratf expr)))))))))
 226
 227 (defun nisletsimp (e)
 228   (let (x)
 229     (cond ((mnump e) e)
 230           ((or (and (atom e) (setq x (ncons e)))
 231                (and (eq (caar e) 'mtimes) (setq x (cdr e))))
 232            (setq x (nisnewlist x))
 233            (if x (nisletsimp ($ratexpand (cons '(mtimes) x))) e))
 234           ((member (caar e) '(mplus mequal mlist $matrix) :test #'eq)
 235            (cons (if (eq (caar e) 'mplus) '(mplus) (car e))
 236                  (mapcar #'nisletsimp (cdr e))))
 237           ((or (eq (caar e) 'mrat)
 238                (and (eq (caar e) 'mquotient) (setq e (ratf e))))
 239            (nisletsimprat e))
 240           (t ;; A kernel (= product of 1 element)
 241            (setq x (nisnewlist (ncons e)))
 242            (if x (nisletsimp ($ratexpand (cons '(mtimes) x))) e)))))
 243
 244 (defun nisletsimprat (e)
 245   (let ((num (cadr e)) (denom (cddr e)) $ratexpand)
 246     (if $letvarsimp (setq varlist (mapcar #'nisletsimp varlist)))
 247     (let (($ratexpand t))
 248       ; Construct new CREs based on the numerator and denominator
 249       ; of E and disrep them in the VARLIST and GENVAR context from
 250       ; E.
 251       ;
 252       ; NISLETSIMP can change VARLIST and GENVAR, so the order of
 253       ; the PDIS and NISLETSIMP forms matter here.  PDISing and
 254       ; NISLETSIMPing the numerator before moving on to the
 255       ; denominator is not correct.
 256       (let ((varlist (mrat-varlist e))
 257             (genvar (mrat-genvar e)))
 258         (setq num (pdis num)
 259               denom (pdis denom)))
 260       (setq num (nisletsimp num)
 261             denom (nisletsimp denom)))
 262     (setq e (list '(mquotient) num denom))
 263     (if $letrat (nisletsimp ($ratexpand e)) e)))
 264
 265 (defun nisnewlist (llist)
 266   (let ((x (nissearch llist nistree nil))) (if x (nisreplace llist x))))
 267
 268 (defun nissearch (x y z)
 269   (cond ((null y) nil)
 270         ((nisinnernull y) (nisfix (nisinnernull y) z))
 271         ((null x) nil)
 272         (t (prog (xx yy path bind)
 273               (setq yy y)
 274               a    (setq xx x)
 275               b    (cond ((and (setq bind (nismatch (car xx)
 276                                                     (caar yy)
 277                                                     z))
 278                                (setq path
 279                                      (nissearch (cdr xx)
 280                                                 (cdar yy)
 281                                                 (cdr bind))))
 282                           (return (cons (car bind) path))))
 283               (setq xx (cdr xx))
 284               (cond (xx (go b)))
 285               (setq yy (cdr yy))
 286               (cond ((null yy) (return nil)))
 287               (go a)))))
 288
 289 (defun nisinnernull (x)
 290   (cond ((null x) nil)
 291         ((null (cdar x)) (caar x))
 292         (t (nisinnernull (cdr x)))))
 293
 294 (defun nisfix (funperd argasslist)
 295   (prog (function args bindings perd flag)
 296      (if (not argasslist) (return (car funperd)))
 297      (setq argasslist (nisnumberpicker argasslist))
 298      (setq args (maplist 'caar argasslist))
 299      (setq bindings (maplist 'cdar argasslist))
 300      (mbinding (args bindings)
 301                (setq function (car funperd))
 302                (if (setq perd (cdr funperd))
 303                    (if (not (meval perd)) (setq flag t)))
 304                (if (null flag) (setq function (meval function))))
 305      (return (if flag nil (list function)))))
 306
 307 (defun nisnumberpicker (x)
 308   (cond ((null x) nil)
 309         ((or (not (symbolp (caar x)))
 310              (kindp (caar x) '$constant))
 311          ;; Skip over numbers and constants
 312          (nisnumberpicker (cdr x)))
 313         (t (nisswcdr x (nisnumberpicker (cdr x))))))
 314
 315 (defun nismatch (a b c)
 316   (prog (x y newexpt)
 317      (setq x (nisextract a))
 318      (setq y (nisextract b))
 319      (cond
 320        ((cadr y)
 321         (cond ((and (equal (car x) (car y))
 322                     (setq c (nisargschecker (cadr x)
 323                                             (cadr y)
 324                                             c))
 325                     (setq newexpt (nisexpocheck (cddr x)
 326                                                 (cddr y)
 327                                                 c)))
 328                (cond ((equal '(rat) (car newexpt))
 329                       (return (cons (cons a (nisbuild x newexpt))
 330                                     c)))
 331                      (t (return (cons (cons a '(dummy 0 (0 0)))
 332                                       newexpt)))))
 333               (t (return nil)))))
 334      (cond ((and (setq c (nisargmatch (niskernel a) (car y) c))
 335                  (setq newexpt (nisexpocheck (cddr x)
 336                                              (cddr y)
 337                                              c)))
 338             (cond ((equal '(rat) (car newexpt))
 339                    (return (cons (cons a (nisbuild x newexpt))
 340                                  c)))
 341                   (t (return (cons (cons a '(dummy 0 (0 0)))
 342                                    newexpt))))))
 343      (return nil)))
 344
 345 (defun niskernel (a)
 346   (if (mexptp a) (cadr a) a))
 347
 348 (defun nisextract (x)
 349   (cond ((or (atom x) (eq (caar x) 'rat))
 350          (cons x (cons nil 1)))
 351         ((eq 'mexpt (caar x))
 352          (cond ((atom (cadr x))
 353                 (cons (cadr x) (cons nil (caddr x))))
 354                (t (cons (if (member 'array (cdaadr x) :test #'eq)
 355                             (list (caaadr x) 'array)
 356                             (caaadr x))
 357                         (cons (cdadr x) (caddr x))))))
 358         (t (cons (if (member 'array (cdar x) :test #'eq)
 359                      (list (caar x) 'array)
 360                      (caar x))
 361                  (cons (cdr x) 1)))))
 362
 363 (defun nisargschecker (listargs treeargs argasslist)
 364   (prog (c)
 365      (cond ((and listargs treeargs) (go check))
 366            ((or listargs treeargs) (return nil))
 367            (t (return argasslist)))
 368      check(setq c (nisargmatch (car listargs)
 369                                (car treeargs)
 370                                argasslist))
 371      (cond (c (return (nisargschecker (cdr listargs)
 372                                       (cdr treeargs)
 373                                       c)))
 374            (t (return nil)))))
 375
 376 (defun nisexpocheck (listpower treepower argasslist)
 377   (prog (p q r s a b xx)
 378      (cond ((atom treepower)
 379             (cond ((numberp treepower)
 380                    (prog2 (setq r treepower s 1) (go math)))
 381                   (t (return (nisargmatch listpower
 382                                           treepower
 383                                           argasslist))))))
 384      (setq r (cadr treepower) s (caddr treepower))
 385      (if (not (numberp s)) (return nil))
 386      math (cond ((numberp listpower) (setq p listpower q 1))
 387                 ((atom listpower) (return nil))
 388                 ((eq 'rat (caar listpower))
 389                  (setq p (cadr listpower) q (caddr listpower)))
 390                 (t (return nil)))
 391      (setq xx (* (* q s) (- (* p s) (* q r))))
 392      (setq a (< (* r s) 0))
 393      (setq b (< xx 0))
 394      (cond ((or (not (or a b)) (and a (or b (equal 0 xx))))
 395             (return (list '(rat) xx (* q s)))))
 396      (return nil)))
 397
 398 (defun nisargmatch (x y c)
 399   (prog (w)
 400      (setq w c)
 401      up   (if (null w) (go down))
 402      (cond ((eq (caar w) y)
 403             (cond ((alike1 (cdar w) x) (return c))
 404                   (t (return nil)))))
 405      (setq w (cdr w))
 406      (go up)
 407      down (setq w (mget y 'matchdeclare))
 408      (cond ((null w) (if (equal x y) (go out) (return nil)))
 409            ((member (car w) '($true t) :test #'eq) (go out))
 410            ((and (atom (car w))
 411                  (meval (cons (ncons (car w))
 412                               (append (cdr w) (list x)))))
 413             (go out))
 414            ((and (not (atom (car w)))
 415                  (not (atom (caar w)))
 416                  (atom (caaar w))
 417          ; If we arrive here, (CAR W) is a Maxima expression like ((FOO) ...)
 418          ; If (CAR W) is a Maxima lambda expression, evaluate it via MFUNCALL.
 419          ; Otherwise, append X and call MEVAL.
 420          ; Note that "otherwise" includes Maxima lambda expressions with missing arguments;
 421          ; in that case the expression is ((MQAPPLY) ((LAMBDA) ...)) and MEVAL is the way to go.
 422                  (if (eq (caaar w) 'lambda)
 423            (mfuncall (car w) x)
 424            (meval (append (car w) (list x)))))
 425             (go out))
 426            (t (return nil)))
 427      out  (return (cons (cons y x) c))))
 428
 429 (defun nisbuild (x newexpt)
 430   (list '(mexpt)
 431         (if (cadr x)
 432             (cons (if (symbolp (car x)) (ncons (car x)) (car x))
 433                   (cadr x))
 434             (car x))
 435         newexpt))
 436
 437 (defun nisreplace (llist asslist)
 438   (cond ((eq (cdr asslist) nil) (cons (car asslist) llist))
 439         ((equal (car llist) (caar asslist))
 440          (cond ((equal 0 (cadar (cdddar asslist)))
 441                 (nisreplace (cdr llist) (cdr asslist)))
 442                (t (cons (cdar asslist)
 443                         (nisreplace (cdr llist) (cdr asslist))))))
 444         (t (cons (car llist) (nisreplace (cdr llist) asslist)))))