bug#37235: 26.1; Precedence error in calc-eval

bug#37235: 26.1; Precedence error in calc-eval

[Charles Karney via Bug reports for GNU Emacs, the Swiss army knife of text editors]

In GNU Emacs 26.1 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.23.2)
  of 2018-08-13 built on buildvm-13.phx2.fedoraproject.org
Windowing system distributor 'Fedora Project', version 11.0.12004000
System Description:	Fedora release 29 (Twenty Nine)

The precedence of calc-eval doesn't follow C-like rules.

   (calc-eval "1/2*3") returns "0.166666666667"

returning the same answer as (calc-eval "1/2/3").  It should return
"1.5".

Configured using:
  'configure --build=x86_64-redhat-linux-gnu
  --host=x86_64-redhat-linux-gnu --program-prefix=
  --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
  --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
  --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
  --libexecdir=/usr/libexec --localstatedir=/var
  --sharedstatedir=/var/lib --mandir=/usr/share/man
  --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
  --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
  --with-gpm=no --with-xwidgets --with-modules
  build_alias=x86_64-redhat-linux-gnu host_alias=x86_64-redhat-linux-gnu
  'CFLAGS=-DMAIL_USE_LOCKF -O2 -g -pipe -Wall -Werror=format-security
  -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions
  -fstack-protector-strong -grecord-gcc-switches
  -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
  -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
  -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
  LDFLAGS=-Wl,-z,relro
  PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS NOTIFY ACL
LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES THREADS XWIDGETS LCMS2

Important settings:
   value of $LC_COLLATE: C
   value of $LC_TIME: C
   value of $LANG: en_US.UTF-8
   value of $XMODIFIERS: @im=none
   locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
   diff-auto-refine-mode: t
   save-place-mode: t
   tooltip-mode: t
   global-eldoc-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-bar-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   blink-cursor-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   line-number-mode: t
   transient-mark-mode: t

Load-path shadows:
/usr/share/emacs/site-lisp/site-start.d/maxima-modes hides 
/usr/share/emacs/site-lisp/maxima/site_start.d/maxima-modes

Features:
(shadow sort emacsbug help-mode cl-print debug calc-alg ispell maxima
maxima-font-lock rect misearch multi-isearch calc-map calc-stat calc-vec
calc-ext calc-menu calc-aent calc calc-loaddefs calc-macs org-table
org-rmail org-mhe org-irc org-info org-gnus nnir gnus-sum gnus-group
gnus-undo gnus-start gnus-cloud nnimap nnmail mail-source tls gnutls
utf7 netrc nnoo parse-time gnus-spec gnus-int gnus-range gnus-win gnus
nnheader wid-edit org-docview doc-view jka-compr image-mode org-bibtex
bibtex org-bbdb org-w3m org-element avl-tree generator org advice
org-macro org-footnote org-pcomplete pcomplete org-list org-faces
org-entities noutline outline org-version ob-emacs-lisp ob ob-tangle
org-src ob-ref ob-lob ob-table ob-keys ob-exp ob-comint comint
ansi-color ring ob-core ob-eval org-compat org-macs org-loaddefs
find-func cal-menu calendar cal-loaddefs vc-git diff-mode easy-mmode
cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs mail-extr message rmc puny dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec epa derived epg epg-config
gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader warnings lpr elec-pair saveplace
edmacro kmacro tempo url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf url-util url-parse url-vars mailcap
xml-parse doxymacs matlab-load cmake-mode thingatpt rx smtpmail
auth-source cl-seq eieio eieio-core eieio-loaddefs password-cache
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
50magit clang-rename clang-include-fixer let-alist json map seq byte-opt
bytecomp byte-compile cconv clang-format cl-macs gv xml cl-loaddefs
cl-lib time-date mule-util tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core term/tty-colors frame cl-generic
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting xwidget-internal
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 295915 64123)
  (symbols 48 39027 3)
  (miscs 40 315 855)
  (strings 32 88008 6139)
  (string-bytes 1 2737911)
  (vectors 16 42045)
  (vector-slots 8 1462820 203824)
  (floats 8 223 624)
  (intervals 56 3321 604)
  (buffers 992 34))

-- 
Charles Karney <charles@karney.com>
Princeton, NJ 08540, USA
https://www.petrel.org

bug#37235: 26.1; Precedence error in calc-eval

[Mauro Aranda]

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tags 37235 notabug
quit

Charles Karney via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

> In GNU Emacs 26.1 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.23.2)
>   of 2018-08-13 built on buildvm-13.phx2.fedoraproject.org
> Windowing system distributor 'Fedora Project', version 11.0.12004000
> System Description: Fedora release 29 (Twenty Nine)
>
> The precedence of calc-eval doesn't follow C-like rules.
>
>    (calc-eval "1/2*3") returns "0.166666666667"
>
> returning the same answer as (calc-eval "1/2/3").  It should return
> "1.5".
>

It works as documented in the Calc manual, section 5.15 Formulas:
C-h i m calc RET 5 m formulas RET

Calc gives '/' lower precedence than '*' by default.

To make Calc follow C-like rules, you can set it with the command
calc-c-language.  You can read its documentation with:
C-h i m calc RET i calc-c-language


Best regards,
Mauro.

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bug#37235: 26.1; Precedence error in calc-eval

[Andreas Schwab]

On Aug 30 2019, Charles Karney via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org> wrote:

> The precedence of calc-eval doesn't follow C-like rules.
>
>    (calc-eval "1/2*3") returns "0.166666666667"
>
> returning the same answer as (calc-eval "1/2/3").  It should return
> "1.5".

It is documented that multiplication has higher precedence than
devision (see (calc) Formulas).  Calc is following the rules of
Algebra.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

bug#37235: 26.1; Precedence error in calc-eval

[Noam Postavsky]

Mauro Aranda <maurooaranda@gmail.com> writes:
>>
>> The precedence of calc-eval doesn't follow C-like rules.
>>
>>    (calc-eval "1/2*3") returns "0.166666666667"
>>
>> returning the same answer as (calc-eval "1/2/3").  It should return
>> "1.5".
>>
>
> It works as documented in the Calc manual, section 5.15 Formulas:
> C-h i m calc RET 5 m formulas RET
>
> Calc gives '/' lower precedence than '*' by default.

Also see (info "(calc) Basic Arithmetic"),

> To make Calc follow C-like rules, you can set it with the command
> calc-c-language.  You can read its documentation with:
> C-h i m calc RET i calc-c-language

which mentions calc-multiplication-has-precedence.

bug#37235: 26.1; Precedence error in calc-eval

[Stefan Kangas]

Mauro Aranda <maurooaranda@gmail.com> writes:
>
> tags 37235 notabug
> quit
>
> Charles Karney via "Bug reports for GNU Emacs, the Swiss army knife of
> text editors" <bug-gnu-emacs@gnu.org> writes:
>
> > In GNU Emacs 26.1 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.23.2)
> >   of 2018-08-13 built on buildvm-13.phx2.fedoraproject.org
> > Windowing system distributor 'Fedora Project', version 11.0.12004000
> > System Description: Fedora release 29 (Twenty Nine)
> >
> > The precedence of calc-eval doesn't follow C-like rules.
> >
> >    (calc-eval "1/2*3") returns "0.166666666667"
> >
> > returning the same answer as (calc-eval "1/2/3").  It should return
> > "1.5".
> >
>
> It works as documented in the Calc manual, section 5.15 Formulas:
> C-h i m calc RET 5 m formulas RET
>
> Calc gives '/' lower precedence than '*' by default.
>
> To make Calc follow C-like rules, you can set it with the command
> calc-c-language.  You can read its documentation with:
> C-h i m calc RET i calc-c-language

Since this is notabug, I'm also closing it.

Best regards,
Stefan Kangas