Opened 14 years ago
Closed 14 years ago
#229 closed defect (fixed)
Bug in ropp_pp_internal_navbit
| Reported by: | Ian Culverwell | Owned by: | Ian Culverwell |
|---|---|---|---|
| Priority: | normal | Milestone: | 5.0 |
| Component: | ropp_pp | Version: | 4.1 |
| Keywords: | open loop navigation bits | Cc: |
Description
Kjartan Kinch (DMI) has identified a bug in the open loop processing routine ropp_pp/preprocess/ropp_pp_openloop.f90. This contains the subroutine ropp_pp_internal_navbit which calculates
TGM(:) = MODULO(time(:), GPSFL)
TGI(:) = INT(time(:)/GPSFL)
Unfortunately, this doesn't quite work:
time = -2.50000000000000 -1.50000000000000 -0.500000000000000
0.500000000000000 1.50000000000000 2.50000000000000
MODULO(time, gpsfl) = 0.500000000000000 0.500000000000000
0.500000000000000 0.500000000000000 0.500000000000000 0.500000000000000
INT(time/gpsfl) = -2 -1 0 0 1 2
Note the double zero in INT.
Problem solved by using FLOOR instead:
FLOOR(time/gpsfl) = -3 -2 -1 0 1 2
TGM+TGI then reconstructs the original time variable correctly.
This fixes some of Kjartan's difficulties in rationalising OCC and ROPP. It has been put right in ROPP5.0.
