[ferret_users] DAYS1900 function

[Brockmann Patrick <Patrick.Brockmann@xxxxxx>]

Hi all,

I would like to compute boundaries of a truemonth (cal=gregorian)
starting in 1860.

I use  the following lines (inspired from truemonth example in 
documentation)

LET start_year = 1860
LET nyears = 5
LET indices = L[L=1:`nyears*12`]
LET month = MOD(indices-1,12)+1
LET year = start_year + INT((indices-1)/12)

DEFINE AXIS/UNITS="seconds"/T0="01-JAN-1860"/EDGES truemonth = 
(DAYS1900(year,month,1)-DAYS1900(1860,1,1))*24*60*60

It works well.
But one can notice that I have used the function DAYS1900 with a year 
argument of 1860.

Is the function still correct in this case ?

It seems that this function calls a Vis5D function to make the 
computation. I cannot find it.

DATE1900(formatted date) Scalar function: converts a formatted date into 
Julian days since 1-Jan-1900.

Thanks
Patrick