diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/ui-calendar.c | 57 |
1 files changed, 30 insertions, 27 deletions
diff --git a/src/ui-calendar.c b/src/ui-calendar.c index 419f7da..9ea31e1 100644 --- a/src/ui-calendar.c +++ b/src/ui-calendar.c @@ -843,8 +843,22 @@ static void adj360(double *deg) } /* + * Phase of the Moon. Calculates the current phase of the moon. + * Based on routines from `Practical Astronomy with Your Calculator', + * by Duffett-Smith. Comments give the section from the book that + * particular piece of code was adapted from. + * + * -- Keith E. Brandt VIII 1984 + * + * Updated to the Third Edition of Duffett-Smith's book, IX 1998 + * + */ + +/* * potm -- - * return phase of the moon + * given number of days since January 1st 1990, 00:00 + * (incl. hours and minutes as a fraction of a day), + * return phase of the moon as a percentage. */ static double potm(double days) { @@ -877,17 +891,6 @@ static double potm(double days) return 50.0 * (1 - cos(dtor(D))); /* sec 67 #3 */ } -/* - * Phase of the Moon. Calculates the current phase of the moon. - * Based on routines from `Practical Astronomy with Your Calculator', - * by Duffett-Smith. Comments give the section from the book that - * particular piece of code was adapted from. - * - * -- Keith E. Brandt VIII 1984 - * - * Updated to the Third Edition of Duffett-Smith's book, IX 1998 - * - */ static double pom(time_t tmpt) { struct tm *GMT; @@ -908,30 +911,30 @@ static double pom(time_t tmpt) /* * Return a pictogram representing the current phase of the moon. - * Careful: date is the selected day in calendar at 00:00, so it represents - * the phase of the moon for previous day. + * Careful: date is the selected day in calendar at 00:00, + * and so represents the phase of the moon at midnight. */ const char *ui_calendar_get_pom(time_t date) { const char *pom_pict[MOON_PHASES] = { " ", "|) ", "(|)", "(| ", " | " }; enum pom phase = NO_POM; - double pom_today, relative_pom, pom_yesterday, pom_tomorrow; const double half = 50.0; - pom_yesterday = pom(date); - pom_today = pom(date + DAYINSEC); - relative_pom = abs(pom_today - half); - pom_tomorrow = pom(date + 2 * DAYINSEC); - if (pom_today > pom_yesterday && pom_today > pom_tomorrow) + date += DAYINSEC / 2; /* adjust to noon */ + double pom_n_b = pom(date - DAYINSEC); /* noon before */ + double pom_m_b = pom(date - DAYINSEC / 2); /* midnight before */ + double pom_n = pom(date); /* noon */ + double pom_m_a = pom(date + DAYINSEC / 2); /* midnight after */ + double pom_n_a = pom(date + DAYINSEC); /* noon after */ + + if (pom_n > pom_n_b && pom_n > pom_n_a) phase = FULL_MOON; - else if (pom_today < pom_yesterday && pom_today < pom_tomorrow) + else if (pom_n < pom_n_b && pom_n < pom_n_a) phase = NEW_MOON; - else if (relative_pom < abs(pom_yesterday - half) - && relative_pom < abs(pom_tomorrow - half)) - phase = - (pom_tomorrow > - pom_today) ? FIRST_QUARTER : LAST_QUARTER; - + else if (pom_m_b < half && half < pom_m_a) + phase = FIRST_QUARTER; + else if (pom_m_b > half && half > pom_m_a) + phase = LAST_QUARTER; return pom_pict[phase]; } |