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SLA_CR2AF - Radians to Deg,Arcmin,Arcsec

ACTION:
Convert an angle in radians to degrees, arcminutes, arcseconds (single precision).
CALL:
CALL sla_CR2AF (NDP, ANGLE, SIGN, IDMSF)
GIVEN:

NDP I number of decimal places of arcseconds
ANGLE R angle in radians
RETURNED:

SIGN C `+' or `$-$'
IDMSF I(4) degrees, arcminutes, arcseconds, fraction
NOTES:
  1. NDP less than zero is interpreted as zero.
  2. The largest useful value for NDP is determined by the size of ANGLE, the format of REAL floating-point numbers on the target machine, and the risk of overflowing IDMSF(4). On some architectures, for ANGLE up to 2pi, 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 a typical 32-bit IDMSF(4).
  3. The absolute value of ANGLE may exceed $2\pi$. In cases where it does not, it is up to the caller to test for and handle the case where ANGLE is very nearly $2\pi$ and rounds up to $360^{\circ}$, by testing for IDMSF(1)=360 and setting IDMSF(1-4) to zero.


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SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
19 December 2005
E-mail:starlink@jiscmail.ac.uk

Copyright © 2013 Science and Technology Facilities Council