Hello all,
I've written a quick patch to allow Remind to calculate astronomical and
nautical twilight, in addition to the existing civil twilight. If other
people find it useful or at least inoffensive, I hope it could be
incorporated into Remind. Thanks for the wonderful program!
Best regards,
Stephen Morgan
diff --git a/man/remind.1 b/man/remind.1
index e430dfe..74425ff 100644
--- a/man/remind.1
+++ b/man/remind.1
@@ -2123,6 +2123,15 @@ be a number as described in the UNIX \fBaccess\fR(2) system call. The
function returns 0 if the file can be accessed with the specified \fImode\fR,
and \-1 otherwise.
.TP
+.B adawn([dq_date])
+Returns the time of "astronomical dawn" on the specified \fIdate\fR. If
+\fIdate\fR is omitted, defaults to \fBtoday()\fR. If a \fIdatetime\fR object
+is supplied, only the date component is used.
+.TP
+.B adusk([dq_date])
+Returns the time of "astronomical twilight" on the specified \fIdate\fR. If
+\fIdate\fR is omitted, defaults to \fBtoday()\fR.
+.TP
.B args(s_fname)
Returns the number of arguments expected by the user-defined function
\fIfname\fR, or \-1 if no such user-defined function exists. Note that
@@ -2517,6 +2526,15 @@ which default to \fBtoday()\fR and midnight, respectively. The returned
value is an integer from 0 to 359, representing the phase of the moon
in degrees. 0 is a new moon, 180 is a full moon, 90 is first-quarter, etc.
.TP
+.B ndawn([dq_date])
+Returns the time of "nautical dawn" on the specified \fIdate\fR. If
+\fIdate\fR is omitted, defaults to \fBtoday()\fR. If a \fIdatetime\fR object
+is supplied, only the date component is used.
+.TP
+.B ndusk([dq_date])
+Returns the time of "nautical twilight" on the specified \fIdate\fR. If
+\fIdate\fR is omitted, defaults to \fBtoday()\fR.
+.TP
.B nonomitted(dq_start, dq_end [,s_wkday...])
This function returns the number of \fInon-\fRomitted days between
\fIstart\fR and \fIend\fR. If \fIstart\fR is non-omitted, then it is
diff --git a/src/funcs.c b/src/funcs.c
index e834789..fbf6066 100644
--- a/src/funcs.c
+++ b/src/funcs.c
@@ -110,6 +110,10 @@ static int FPsshade (func_info *);
static int FShell (func_info *);
static int FStrlen (func_info *);
static int FSubstr (func_info *);
+static int FADawn (func_info *);
+static int FADusk (func_info *);
+static int FNDawn (func_info *);
+static int FNDusk (func_info *);
static int FDawn (func_info *);
static int FDusk (func_info *);
static int FSunset (func_info *);
@@ -188,6 +192,8 @@ BuiltinFunc Func[] = {
{ "abs", 1, 1, 1, FAbs },
{ "access", 2, 2, 0, FAccess },
+ { "adawn", 0, 1, 0, FADawn},
+ { "adusk", 0, 1, 0, FADusk},
{ "args", 1, 1, 0, FArgs },
{ "asc", 1, 1, 1, FAsc },
{ "baseyr", 0, 0, 1, FBaseyr },
@@ -233,6 +239,8 @@ BuiltinFunc Func[] = {
{ "moondatetime", 1, 3, 0, FMoondatetime },
{ "moonphase", 0, 2, 0, FMoonphase },
{ "moontime", 1, 3, 0, FMoontime },
+ { "ndawn", 0, 1, 0, FNDawn},
+ { "ndusk", 0, 1, 0, FNDusk},
{ "nonomitted", 2, NO_MAX, 0, FNonomitted },
{ "now", 0, 0, 0, FNow },
{ "ord", 1, 1, 1, FOrd },
@@ -1878,9 +1886,6 @@ static int SunStuff(int rise, double cosz, int jul)
FromJulian(jul, &year, &mon, &day);
- if (rise > 1)
- rise -= 2;
-
/* Following formula on page B6 exactly... */
t = (double) jul;
if (rise) {
@@ -1970,19 +1975,28 @@ static int SunStuff(int rise, double cosz, int jul)
static int FSun(int rise, func_info *info)
{
int jul = JulianToday;
- double cosz = -0.014543897; /* for sunrise and sunset */
+ double cosz;
int r;
+ if (rise == 0 || rise == 1) {
+ /* Sunrise and sunset : cos(90 degrees + 50 arcminutes) */
+ cosz = -0.01454389765158243;
+ } else if (rise == 2 || rise == 3) {
/* Civil twilight: cos(96 degrees) */
- if (rise == 2 || rise == 3) {
- cosz = -0.104528463268;
+ cosz = -0.10452846326765333;
+ } else if (rise == 4 || rise == 5) {
+ /* Nautical twilight: cos(102 degrees) */
+ cosz = -0.20791169081775912;
+ } else if (rise == 6 || rise == 7) {
+ /* Astronomical twilight: cos(108 degrees) */
+ cosz = -0.30901699437494734;
}
if (Nargs >= 1) {
if (!HASDATE(ARG(0))) return E_BAD_TYPE;
jul = DATEPART(ARG(0));
}
- r = SunStuff(rise, cosz, jul);
+ r = SunStuff(rise % 2, cosz, jul);
if (r == NO_TIME) {
RETVAL = 0;
RetVal.type = INT_TYPE;
@@ -2014,6 +2028,24 @@ static int FDusk(func_info *info)
return FSun(2, info);
}
+static int FNDawn(func_info *info)
+{
+ return FSun(5, info);
+}
+static int FNDusk(func_info *info)
+{
+ return FSun(4, info);
+}
+
+static int FADawn(func_info *info)
+{
+ return FSun(7, info);
+}
+static int FADusk(func_info *info)
+{
+ return FSun(6, info);
+}
+
/***************************************************************/
/* */
/* FFiledate */
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