[ferret_users] @FLN along a time axis with unit=seconds returns *nan*

["Paulo B. Oliveira" <pbo@xxxxxxxxx>]

Hi,

I realized that @FLN returns a *nan* when interpolating along a time
axis with units of seconds. It seems an issue related with the huge
numbers involved when T0 is very far from the actual axis dates. I
suggest that ferret issue a warning and set the output to the usual BAD
value instead of *nan*. A jnl to show this is attached:

yes? go fln_tsec
 ! NOAA/PMEL TMAP
 ! FERRET v6.5
 ! Linux(g77) 2.4.21-57.ELsmp - 04/01/10
 ! 16-Sep-10 13:41
 
def ax/t="16-sep-2010 13:00":"16-sep-2010 13:02":15/unit=sec t15s
 let v1 = if l[gt=t15s] lt 5 then 1
 let v2 = if l[gt=t15s] gt 5 then 2
 let v1_2 = if v1 then v1 else v2
list v1_2,v1_2[t=@fln]
             TIME: 16-SEP-2010 12:59 to 16-SEP-2010 13:02
 Column  1: V1_2 is IF V1 THEN V1 ELSE V2
 Column  2: V1_2[T=@FLN:1] is IF V1 THEN V1 ELSE V2 (linear-filled by 1
pts on T)
                           V1_2   V1_2
16-SEP-2010 13:00:00 / 1:  1.000  1.000
16-SEP-2010 13:00:15 / 2:  1.000  1.000
16-SEP-2010 13:00:30 / 3:  1.000  1.000
16-SEP-2010 13:00:45 / 4:  1.000  1.000
16-SEP-2010 13:01:00 / 5:   ....    nan
16-SEP-2010 13:01:15 / 6:  2.000  2.000
16-SEP-2010 13:01:30 / 7:  2.000  2.000
16-SEP-2010 13:01:45 / 8:  2.000  2.000
16-SEP-2010 13:02:00 / 9:  2.000  2.000
 
def ax/t="16-sep-2010 13:00":"16-sep-2010
13:02":15/unit=sec/t0="16-sep-2010 12:59" t15s
Replacing definition of axis T15S
 let v1 = if l[gt=t15s] lt 5 then 1
 let v2 = if l[gt=t15s] gt 5 then 2
 let v1_2 = if v1 then v1 else v2
list v1_2,v1_2[t=@fln]
             TIME: 16-SEP-2010 12:59 to 16-SEP-2010 13:02
 Column  1: V1_2 is IF V1 THEN V1 ELSE V2
 Column  2: V1_2[T=@FLN:1] is IF V1 THEN V1 ELSE V2 (linear-filled by 1
pts on T)
                           V1_2   V1_2
16-SEP-2010 13:00:00 / 1:  1.000  1.000
16-SEP-2010 13:00:15 / 2:  1.000  1.000
16-SEP-2010 13:00:30 / 3:  1.000  1.000
16-SEP-2010 13:00:45 / 4:  1.000  1.000
16-SEP-2010 13:01:00 / 5:   ....  1.500
16-SEP-2010 13:01:15 / 6:  2.000  2.000
16-SEP-2010 13:01:30 / 7:  2.000  2.000
16-SEP-2010 13:01:45 / 8:  2.000  2.000
16-SEP-2010 13:02:00 / 9:  2.000  2.000


 ! NOAA/PMEL TMAP
 ! FERRET v6.5  
 ! Linux(g77) 2.4.21-57.ELsmp - 04/01/10
 ! 16-Sep-10 13:41     

def ax/t="16-sep-2010 13:00":"16-sep-2010 13:02":15/unit=sec t15s
 let v1 = if l[gt=t15s] lt 5 then 1
 let v2 = if l[gt=t15s] gt 5 then 2
 let v1_2 = if v1 then v1 else v2
list v1_2,v1_2[t=@fln]

def ax/t="16-sep-2010 13:00":"16-sep-2010 13:02":15/unit=sec/t0="16-sep-2010 12:59" t15s
 let v1 = if l[gt=t15s] lt 5 then 1
 let v2 = if l[gt=t15s] gt 5 then 2
 let v1_2 = if v1 then v1 else v2
list v1_2,v1_2[t=@fln]