**ACTION:**- Convert an interval in days into hours, minutes, seconds
(double precision).
**CALL:**`CALL sla_DD2TF (NDP, DAYS, SIGN, IHMSF)`

**GIVEN:**-

*NDP***I**number of decimal places of seconds *DAYS***D**interval in days

**RETURNED:**-

*SIGN***C**`+' or `-' *IHMSF***I(4)**hours, minutes, seconds, fraction

**NOTES:**- 1.
- NDP less than zero is interpreted as zero.
- 2.
- The largest useful value for NDP is determined by the size of DAYS, the format of DOUBLE PRECISION floating-point numbers on the target machine, and the risk of overflowing IHMSF(4). For example, on a VAX computer, for DAYS up to 1D0, the available floating-point precision corresponds roughly to NDP=12. However, the practical limit is NDP=9, set by the capacity of the 32-bit integer IHMSF(4).
- 3.
- The absolute value of DAYS may exceed 1D0. In cases where it does not, it is up to the caller to test for and handle the case where DAYS is very nearly 1D0 and rounds up to 24 hours, by testing for IHMSF(1)=24 and setting IHMSF(1-4) to zero.

Starlink User Note 67

P. T. Wallace

12 October 1999

E-mail:ptw@star.rl.ac.uk