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Cleaned up documentation

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This commit is contained in:
Sudhir Shenoy 2017-07-15 12:33:54 +09:00
parent 28604b19d4
commit 6727b123cd
6 changed files with 108 additions and 55 deletions
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48
dates.lisp
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@ -27,22 +27,23 @@
(in-package :cl-dates)
(defun jday-number (date)
"Returns the Julian day number for the given Julian date"
"Returns the Julian day number for the given date-time"
(floor (+ date 1/2)))
(defparameter +days-of-week+ #(:monday :tuesday :wednesday :thursday :friday :saturday :sunday))
(defun day-of-week (date)
"Returns the day of week on which the given Julian date falls"
"Returns the day of week on which the given date falls"
(aref +days-of-week+ (mod (jday-number date) 7)))
(defun ymd->date (yy mm dd &optional (hour 0) (min 0) (sec 0) zone)
"Return the Julian date corresponding to the given date and time. No
compensation is made for the Gregorian Calendar introduction.
Note that the Julian date is an integer when the time is noon so a
date without time (midnight) will have a fractional part of 0.5.
"Return the date-time corresponding to the given date and (optionally) time.
If timezone is specified, it should be either an alphabetic code e.g., \"IST\"
or a numeric offset in fractions of an hour e.g., +5.5"
No adjustment is made for the Gregorian Calendar introduction. Note that the
Julian date is defined to begin at noon so a date without time (midnight) will
have a fractional part of 0.5.
If timezone is specified, it should be either an alphabetic code or numeric offset
from UTC e.g., for Indian Standard time, it should be specified as \"IST\" or +5.5"
(let* ((a (floor (* 1/12 (- 14 mm))))
(b (- yy a))
(c (floor (/ b 100)))
@ -58,9 +59,9 @@ or a numeric offset in fractions of an hour e.g., +5.5"
(- jdate (/ offset 24))))
(defun date->ymd (date &key (want-time nil))
"Returns 6 values if :want-time is true: year, month, day, hour, minute, second.
Second may be a floating point value but the first five are aways integers.
If :want-time is NIL, returns year, month and day as integers."
"Returns 6 values if want-time is true: year, month, day, hour, minute, second.
The second may be a floating point value but the first five are aways integers.
If want-time is NIL, only three integer values are returned - year, month and day."
(let* ((jd (jday-number date))
(e (floor (/ (- jd 1867216.25d0) 36524.25d0)))
(f (+ 1 jd e (- (floor (/ e 4)))))
@ -84,8 +85,17 @@ If :want-time is NIL, returns year, month and day as integers."
(defun valid-date-p (yy mm dd)
"Check that year, month and day form a valid calendar date"
(multiple-value-bind (y m d) (date->ymd (ymd->date yy mm dd))
(and (= yy y) (= mm m) (= dd d))))
(cond ((not (and (integerp yy) (> yy -4713)
(integerp mm) (<= 1 mm 12)
(integerp dd) (<= 1 dd 31)))
nil)
((and (or (= mm 4) (= mm 6) (= mm 9) (= mm 11)) (> dd 30))
nil)
((and (leap-year-p yy) (= mm 2) (> dd 29))
nil)
((and (not (leap-year-p yy)) (= mm 2) (> dd 28))
nil)
(t t)))
(defun valid-time-p (h m s)
"Check that hour, minute and second are valid numbers"
@ -114,8 +124,8 @@ If :want-time is NIL, returns year, month and day as integers."
(defun easter-day (yy &optional (want-gregorian-date nil))
"Returns the date for Easter Sunday in the given year.
Accurate until approx. 4000 CE
Returns a Julian date if want-gregorian-date is NIL. Otherwise,
it returns year, month, day, hour, minute and second as 6 values"
Returns a date if want-gregorian-date is NIL. Otherwise,
it returns year, month, day as 3 values"
(let* ((century (floor (/ yy 100)))
(remain-19 (mod yy 19))
(temp (+ (floor (* 1/2 (- century 15)))
@ -152,22 +162,22 @@ it returns year, month, day, hour, minute and second as 6 values"
(defun vernal-equinox (yy &optional (want-gregorian-date nil))
"Return UTC date-time of the vernal (spring) equinox for the given year.
Returns a Julian date if want-gregorian-date is NIL. Otherwise,
Returns a date-time if want-gregorian-date is NIL. Otherwise,
it returns year, month, day, hour, minute and second as 6 values"
(calc-equinox-or-solstice-date 1 yy want-gregorian-date))
(defun summer-solstice (yy &optional (want-gregorian-date nil))
"Return UTC date-time of the summer solstice for the given year.
Returns a Julian date if want-gregorian-date is NIL. Otherwise,
Returns a date-time if want-gregorian-date is NIL. Otherwise,
it returns year, month, day, hour, minute and second as 6 values"
(calc-equinox-or-solstice-date 2 yy want-gregorian-date))
(defun autumnal-equinox (yy &optional (want-gregorian-date nil))
"Return UTC date-time of the autumnal equinox for the given year.
Returns a Julian date if want-gregorian-date is NIL. Otherwise,
Returns a date-time if want-gregorian-date is NIL. Otherwise,
it returns year, month, day, hour, minute and second as 6 values"
(calc-equinox-or-solstice-date 3 yy want-gregorian-date))
(defun winter-solstice (yy &optional (want-gregorian-date nil))
"Return UTC date-time of the winter solstice for the given year.
Returns a Julian date if want-gregorian-date is NIL. Otherwise,
Returns a date-time if want-gregorian-date is NIL. Otherwise,
it returns year, month, day, hour, minute and second as 6 values"
(calc-equinox-or-solstice-date 4 yy want-gregorian-date))