sub abs_day { # this subroutine accepts a month, day, and two-digit year in # mm/dd/yy numerical form, e.g., 3/23/04. # it then calculates the "absolute day", # i.e., the number of days # since day 0, which is the turn of the 21st century. # so, 1/10/2000 is absolute day 10; # 1/10/2001 is absolute day 376 # (because year 2000 was a leap year). # the routine deals with leap years by # multiplying years by 365.25, and then rounding down. my \$month = shift(@_); my \$day = shift(@_); my \$year = shift(@_); if (\$debug) { print "i'm in abs_day and month is \$month,", " day is \$day, year is \$year\n"; } my \$abs_day; undef(\$abs_day); # so each year has 365.25 days # years are of the form 00, 01, 02, etc. \$abs_day = \$year * 365.25; # add .75 to account for fact that year 00 is a leap year \$abs_day = \$abs_day + .75; if (\$debug) { print "abs_day is \$abs_day after adding .75 to yr*365\n"; } if (\$month == 1) #jan { \$abs_day = \$abs_day + 0; } if (\$month == 2) #feb { \$abs_day = \$abs_day + 31; } # starting in march, we add .25 to number of days # to account for leap year if (\$month == 3) #mar { \$abs_day = \$abs_day + 59.25; } if (\$month == 4) #apr { \$abs_day = \$abs_day + 90.25; } if (\$month == 5) #may { \$abs_day = \$abs_day + 120.25; } if (\$month == 6) #jun { \$abs_day = \$abs_day + 151.25; } if (\$month == 7) #jul { \$abs_day = \$abs_day + 181.25; } if (\$month == 8) #aug { \$abs_day = \$abs_day + 212.25; } if (\$month == 9) #sep { } if (\$month == 11) #nov { \$abs_day = \$abs_day + 304.25; } if (\$month == 12) #dec { \$abs_day = \$abs_day + 334.25; } \$abs_day = \$abs_day + \$day; if (\$debug) { print "now that we have added year, month, and", " day, abs_day is \$abs_day\n"; } \$abs_day = sprintf "%d", \$abs_day; if (\$debug) { print "now that we have converted from float to integer,", " abs_day is \$abs_day\n"; } return \$abs_day; }