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

 Hi Paulo,
Thank you for the report, and the example. There is enough precision to store the time coordinates in seconds, even starting with year 0, using the double-precision storage Ferret uses for coordinate data.  But single precision is used for other storage including variables. It should be possible to fix this, and not need a warning or bad-value.

Ansley

On 9/16/2010 6:22 AM, Paulo B. Oliveira wrote:

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
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