Convert an interval in days to hours, minutes, seconds
CALL sla_CD2TF (NDP, DAYS, SIGN, IHMSF)
number of decimal places of seconds
interval in days
`+' or `-'
hours, minutes, seconds, fraction
NDP less than zero is interpreted as zero.
The largest useful value for NDP is determined by the size of
DAYS, the format of REAL floating-point numbers on the target
machine, and the risk of overflowing IHMSF(4). For example,
on a VAX computer, for DAYS up to 1.0, the available floating-point
precision corresponds roughly to NDP=3. This is well below
the ultimate limit of NDP=9 set by the capacity of the 32-bit
The absolute value of DAYS may exceed 1.0. In cases where it
does not, it is up to the caller to test for and handle the
case where DAYS is very nearly 1.0 and rounds up to 24 hours,
by testing for IHMSF(1)=24 and setting IHMSF(1-4) to zero.