No problem, though a good thing you replied because I just saw I forgot the leap year case (add 1 day after February).
Put this code in the date picker OnChange :
Set(
_month,
Text(
DateTimeValue(DatePicker3_1.SelectedDate),
"[$-en-GB]mm"
)
);
Set(
_day,
Text(
DateTimeValue(DatePicker3_1.SelectedDate),
"[$-en-GB]dd"
)
);
Set(_leapYear, If(Month(Date(Year(Now()),2,29))=2, 1, 0)); // If leap year add 1 to _jday
Set(
_jDay,
Switch(
_month,
"01",
"0" & _day,
"02",
"0" & Value(_day)+31,
"03",
"0" & Value(_day)+59 +_leapYear,
"04",
"0" & Value(_day)+90 +_leapYear,
"05",
Value(_day)+120 +_leapYear,
"06",
Value(_day)+151 +_leapYear,
"07",
Value(_day)+181 +_leapYear,
"08",
Value(_day)+212 +_leapYear,
"09",
Value(_day)+243 +_leapYear,
"10",
Value(_day)+273 +_leapYear,
"11",
Value(_day)+304 +_leapYear,
"12",
Value(_day)+334 +_leapYear
)
);
Set(julianDate, Text(
DateTimeValue(DatePicker3_1.SelectedDate),
"[$-en-GB]yy"
) & _jDay)