[ncl-talk] A bug of use cd_calendar , second = 60

Sun Feb 19 15:14:37 MST 2017

Xiaobin,

There is a known bug in the cd_calendar function in NCL version 6.3.0.  For
time values that are extremely close to 0 or 60 seconds, the function
sometimes outputs 60 seconds, and fails to increment the number of
minutes.  Notice in your original message, some of the output values for
minutes were incorrect, as well as values for seconds.  This bug should be
fixed in the next NCL release.

In the meantime, you may be able to avoid the bug by adding a small
fraction of one minute to your time values.  This should work because it
seems like your intended values are even minutes with zero seconds:

  time(:) = time(:) + (0.01 / 3600)     ; add 0.01 seconds to "hours
since..."
  print (sprintf ("%24.11f", time))

(0)     3615141.00000277767
(1)     3615141.08333611069
(2)     3615141.16666944465
(3)     3615141.25000277767
(4)     3615141.33333611069
(5)     3615141.41666944465
(6)     3615141.50000277767
(7)     3615141.58333611069
(8)     3615141.66666944465
(9)     3615141.75000277767
(10)    3615141.83333611069
(11)    3615141.91666944465
(12)    3615142.00000277767
(13)    3615142.08333611069
(14)    3615142.16666944465
(15)    3615142.25000277767

Now your code to compute hours, minutes, seconds, etc. with cd_calendar
seems to work okay.  When you use "tointeger", the extra 0.01 seconds is
removed safely:

second = tointeger (utc_date(:,5))
etc.

  print (date_str)

(0) 2013_05_31_21_00_00
(1) 2013_05_31_21_05_00
(2) 2013_05_31_21_10_00
(3) 2013_05_31_21_15_00
(4) 2013_05_31_21_20_00
(5) 2013_05_31_21_25_00
(6) 2013_05_31_21_30_00
(7) 2013_05_31_21_35_00
(8) 2013_05_31_21_40_00
(9) 2013_05_31_21_45_00
(10) 2013_05_31_21_50_00
(11) 2013_05_31_21_55_00
(12) 2013_05_31_22_00_00
(13) 2013_05_31_22_05_00
(14) 2013_05_31_22_10_00
(15) 2013_05_31_22_15_00

Please check all output values to make sure this fix works for all cases in
your data.

--Dave

On Sun, Feb 19, 2017 at 1:55 AM, qiuxiaobin.tj <qiuxiaobin.tj at qq.com> wrote:

> *Dear all*
>
> *I met a bug when use cd_calendar. Some times it return second = 60.*
> *Here is the input time:*
> Variable: time
> Type: double
> Total Size: 680 bytes
>             85 values
> Number of Dimensions: 1
> Dimensions and sizes: [time | 85]
> Coordinates:
> Number Of Attributes: 3
>   _FillValue : 9.969209968386869e+36
>   calendar : gregorian
>   units : hours since 1601-01-01 00:00:0.0
> (0) 3615141
> (1) 3615141.083333333
> (2) 3615141.166666667
> (3) 3615141.25
> (4) 3615141.333333333
> (5) 3615141.416666667
> (6) 3615141.5
> (7) 3615141.583333333
> (8) 3615141.666666667
> (9) 3615141.75
> (10) 3615141.833333333
> (11) 3615141.916666667
> (12) 3615142
> (13) 3615142.083333333
> (14) 3615142.166666667
> (15) 3615142.25
> ..............
>
> *Here is the scripts:*
>
> utc_date = cd_calendar(time, 0)
> ;
> ; Store return information into more meaningful variables.
> ;
> year   = tointeger(utc_date(:,0))    ; Convert to integer for
> month  = tointeger(utc_date(:,1))    ; use sprinti
> day    = tointeger(utc_date(:,2))
> hour   = tointeger(utc_date(:,3))
> minute = tointeger(utc_date(:,4))
> second = tointeger(utc_date(:,5))
>
> ; Write out strings in the format "hhZ dd mmm yyyy".
>
> date_str = sprinti("%0.4i",year) + "_" + sprinti("%0.2i",month) + "_" +
> sprinti("%0.2i",day) + "_" + sprinti("%0.2i",hour) + "_" +
> sprinti("%0.2i",minute) + "_" + sprinti("%0.2i",second)
>
> print(date_str)
>
> *Here is the output:*
> Variable: date_str
> Type: string
> Total Size: 680 bytes
>             85 values
> Number of Dimensions: 1
> Dimensions and sizes: [85]
> Coordinates:
> (0) 2013_05_31_21_00_00
> (1) 2013_05_31_21_05_00
> (2) 2013_05_31_21_*09_60*
> (3) 2013_05_31_21_15_00
> (4) 2013_05_31_21_20_00
> (5) 2013_05_31_21_*24_60*
> (6) 2013_05_31_21_30_00
> (7) 2013_05_31_21_35_00
> (8) 2013_05_31_21_*39_60*
> (9) 2013_05_31_21_45_00
> (10) 2013_05_31_21_50_00
> (11) 2013_05_31_21_*54_60*
> (12) 2013_05_31_22_00_00
> (13) 2013_05_31_22_05_00
> (14) 2013_05_31_22_*09_60*
> (15) 2013_05_31_22_15_00
>
> *How to overcome this? Thanks a lot.*
>
> *Best,*
> *Xiaobin*
>
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