The CDF_EPOCH_COMPARE function compares two epoch (date and time) values.
Values can be scalars or an array of values. The epoch can be one of the CDF formats, CDF_EPOCH, CDF_EPOCH16 or CDF_TIME_TT2000. While data of type CDF_EPOCH and CDF_EPOCH16 can be compared with each other, data in CDF_TIME_TT2000 can be compared only with data of the same type.
If the base epoch is a scalar, it is used to compare with all values in the first epoch. If the base epoch is an array, the same element in the source and base epoch array is compared. If a third argument, endepoch, is provided, the baseepoch and endepoch are used as the starting and ending epoch that the source epoch will be checked against.
Result = CDF_EPOCH_COMPARE(epoch, baseepoch, [endepoch])
If the function uses two arguments, the return value is a scalar value or an array of integer values (1, 0, or -1), depending on the source epoch.
If the value of the first epoch is greater (later date and time) than the base epoch, 1 is set.
If the value of the first epoch is the same as the base epoch, 0 is set.
If the value of the first epoch is less (earlier date and time) than the base epoch, -1 is set.
| Result | Condition |
|---|---|
|
1 |
if epoch1 > baseepoch |
|
0 |
if epoch1 = baseepoch |
|
-1 |
if epoch1 < baseepoch |
If the function uses three arguments, the return value is a scalar value or an array of integer values (1 or 0).
If the value of the source epoch falls within the starting and ending epoch, 1 is set. Otherwise, 0 is set.
| 1 | if baseepoch <= epoch1 <= endepoch |
| 0 | Otherwise |
A single or an array of epoch value(s) returned from:
A single or an array of epoch value(s) returned from:
A single or an array of epoch value(s) returned from:
Note: This field must be of the same data type and dimensionality as baseepoch.
None
; For CDF_EPOCH data type
CDF_VARGET, id, "Epoch", ep, REC_COUNT=1000,/ZVARIABLE
CDF_EPOCH, base, 2005,6,1,10,18,17,2,/COMPUTE
ret= CDF_EPOCH_COMPARE(ep,base)
HELP, ret
; For CDF_TIME_TT2000 data type
CDF_VARGET, id2, "Epoch", ep2, REC_COUNT=1000,/ZVARIABLE
CDF_TT2000, base2, 2005,6,1,10,18,17,2,3,4,/COMPUTE
ret2= CDF_EPOCH_COMPARE(ep2,base2)
HELP, ret2
; For CDF_EPOCH data type
CDF_VARGET, id3, "Epoch", ep3, REC_COUNT=1000,/ZVARIABLE
CDF_EPOCH, starting, 2005,6,1,10,18,17,2,/COMPUTE
CDF_EPOCH, ending, 2005,6,10,10,18,17,2,/COMPUTE
ret3= CDF_EPOCH_COMPARE(ep3,starting,ending)
HELP, ret3
|
6.4 |
Introduced |