bug#36822: 26.2; Calc: calc-julian produces incorrect result

[Michel Schinz]

To reproduce:

- start calc (M-x calc)

- enter algebraic mode (')

- enter today's date as <2019-07-27> then hit RET

- convert to Julian day count (t J)

- notice that the result is 2458690, which is wrong (the correct value

  is 2458692)

Oddly enough, Emacs' calendar produces the correct value. To see this,

start the calendar (M-x calendar), navigate to the date above, then

press "p a". This displays the correct value:

Astronomical (Julian) day number (at noon UTC): 2458692.0

To cross-check, several web sites are available to compute the Julian

day number, e.g. http://numerical.recipes/julian.html

In GNU Emacs 26.2 (build 1, x86_64-apple-darwin18.2.0, NS appkit-1671.20 Version 10.14.3 (Build 18D109))

of 2019-04-13 built on builder10-14.porkrind.org

Windowing system distributor 'Apple', version 10.3.1671

Recent messages:

For information about GNU Emacs and the GNU system, type C-h C-a.

user-error: The mark is not set now, so there is no region

Welcome to the GNU Emacs Calculator!  Press ‘?’ or ‘h’ for help, ‘q’ to quit

<help> DEL is undefined

Configured using:

'configure --with-ns '--enable-locallisppath=/Library/Application

Support/Emacs/${version}/site-lisp:/Library/Application

Support/Emacs/site-lisp' --with-modules'

Configured features:

NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES THREADS

Important settings:

  value of $LANG: fr_CH.UTF-8

  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:

  tooltip-mode: t

  global-eldoc-mode: t

  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:

None found.

Features:

(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv

bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs

format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config

gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse

rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045

ietf-drums mm-util mail-prsvr mail-utils calccomp calc-arith calc-alg

calc-misc calc-vec calc-forms calc-ext calc-aent calc-menu easymenu calc

calc-loaddefs calc-macs elec-pair time-date tooltip eldoc electric

uniquify ediff-hook vc-hooks lisp-float-type mwheel term/ns-win ns-win

ucs-normalize mule-util term/common-win 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 threads kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:

((conses 16 238377 12447)

(symbols 48 23518 1)

(miscs 40 46 241)

(strings 32 36281 1818)

(string-bytes 1 950248)

(vectors 16 37616)

(vector-slots 8 761908 14102)

(floats 8 51 104)

(intervals 56 230 0)

(buffers 992 13))