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8.4.1
ISO Duration and double |
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The functions in this section perform the interconversion of the ISO_DURATION structure and a type double value, which is a floating point representation of a period of time, not a Julian Day number. The floating point value can be treated as the difference between two Julian day numbers. |
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8.4.1.1
iso_duration_to_double () |
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The routine iso_duration_to_double () (Listing 8.3) converts an elapsed time, combined as an ISO_DURATION structure, to a type double. |
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| Listing 8.3 iso_duration_to_double () | |
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/* idur2dl.c
+-------------------------------------------+
| Copyright (C) 1995 by Lance W. Latham. |
| All rights reserved. |
+-------------------------------------------+
Routine converts an elapsed time, combined as an ISO_DURATION
structure, to a type double.
INPUTS:
1. duration, pointer to an ISO_DURATION structure containing the
elapsed days as a DATE_INFO structure (standard year, standard
month and day) and the elapsed time as a TIME_INFO structure
(hours, minutes and seconds).
OUTPUTS:
1. Returned by routine, type double, assumed to be the difference
between two Julian Day numbers.
NOTES:
1. This routine converts a duration of elapsed time into a difference
between two Julian day numbers, expressed as a type double. To
convert a date and time to its equivalent Julian Day number, use
the ISO_DATE_TIME structure and the routine in this series,
'iso_date_time_to_double ()'.
2. Negative values of any units for either the 'date' or 'time'
portions of the duration are inverted to produce a positive value,
prior to use. No other validation is performed, and no warning is
issued in this case.
3. Note that the value returned by this routine is a difference
between two Julian Day numbers. Specifically, the fractional
portion of this value is NOT a displacement from 0.0 (noon),
as is the case with the 'time_to_fraction ()' routine.
*/
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