#ifndef UNITS_H
#define UNITS_H

#include "prconst.h"

/* first the group of macors that deal with constants, then the group
   that uses the first group */

/** Convert arcseconds to degrees */
#define ARCSEC2DEG(a) ((a)/3600.)

/** Convert milli-arcseconds to degrees */
#define MAS2DEG(m) ((m)/1.e6/3600.)

/** Convert degrees to arcseconds */
#define DEG2ARCSEC(d) (3600.*(d))

/** Convert arc-minutes to degrees */
#define ARCMIN2DEG(a) ((a)/60.)

/** Convert degrees to radians */
#define DEG2RAD(d) (M_PI*(d)/180.)

/** Convert radians to degrees */
#define RAD2DEG(r) (180.*(r)/M_PI)

/** Convert wavelength [microns] to spectroscopic wavenumbers
* [1/cm=kayser].
*/
#define MICRON2WN(m) (1.e4/(m))

/** Convert spectroscopic wavenumber [1/cm=kayser]
* into wavelength [microns]
*/
#define WN2MICRON(w) (1.e4/(w))

/** Convert momentum measured in [1/m] to spectroscopic wavenumber [1/cm=kayser]
* The parameter \c k multiplied with a distance [m] would give a phase [radians],
* so the difference between momentum and spectroscopic wavenumber used elsewhere
* is the factor 2 pi and the factor 100 for conversion of 1/cm to 1/m.
*/
#define K2KAYSER(k) ((k)/(2.*M_PI*100.))
#define KAYSER2K(k) (2.*M_PI*100.*(k))

/** Convert momentum measured in [1/m] to wavelength [micron] */
#define K2MICRON(k) (2.*M_PI*1.e6/(k))

/** Convert wavelength [micron] to momentum measured in [1/m] */
#define MICRON2K(m) (2.*M_PI*1.e6/(m))

/** Convert spectroscopic wavenumber [1/cm] to frequency [Hz] */
#define WN2HZ(w) (100.*VACUUMC*(w))

/** Convert frequency [Hz] to spectroscopic wavenumber [1/cm] */
#define HZ2WN(h) ((h)/(100.*VACUUMC))

/** convert Kelvin to Celsius */
#define KELVIN2CELS(k) ((k)-273.15)
/** convert Celsius to Kelvin */
#define CELS2KELVIN(c) ((c)+273.15) 

/** convert radians to arcseconds */
#define RAD2ARCSEC(r) (DEG2ARCSEC(RAD2DEG(r)))

/** convert arcseconds to radians */
#define ARCSEC2RAD(a) (DEG2RAD(ARCSEC2DEG(a)))

/** convert arc-minutes to radians */
#define ARCMIN2RAD(a) (DEG2RAD(ARCMIN2DEG(a)))

/** convert diameter to circle surface area */
#define D2AREA(d) (M_PI_4*(d)*(d))

#endif /* UNITS_H */

/*
$Log:$
*/