planets/planets.c
/*
 * NASA JPL expresses azimuth as degrees East of North, which is
 * the default representation. However, Kerry Shetline's excellent
 * SkyViewCafe presents ZD as "Altitude", and Azimuth is presented
 * as "degrees West of South".
 *
 * When the global <f_azi_s> is non-zero, express azimuth as
 * degrees West of South instread of degrees East of North.
 *
 * This function adjusts the equ2hor ZD/AZ values to match SkyViewCafe.
 */
NASA JPL expresses azimuth as degrees East of North, which is
the default representation. However, Kerry Shetline's excellent
SkyViewCafe presents ZD as "Altitude", and Azimuth is presented
as "degrees West of South".

When the global  is non-zero, express azimuth as
degrees West of South instread of degrees East of North.

This function adjusts the equ2hor ZD/AZ values to match SkyViewCafe.
NASA JPL expresses azimuth as degrees East of North which is the default representation . However Kerry Shetline ' s excellent SkyViewCafe presents ZD as " Altitude " and Azimuth is presented as " degrees West of South " . When the global is non - zero express azimuth as degrees West of South instread of degrees East of North . This function adjusts the equ2hor ZD / AZ values to match SkyViewCafe .
void correct_zd_az(double *zd, double *az) {
    if (f_azi_s) {
        *az = normalize(*az - 180.0, 360.0);
    } else {
        *az = normalize(*az, 360.0);
    }
    *zd = 90.0 - *zd;
}
void correct_zd_az ( double * zd , double * az ) { if ( f_azi_s ) { * az = normalize ( * az - 180.0 , 360.0 ) ; } else { * az = normalize ( * az , 360.0 ) ; } * zd = 90.0 - * zd ; }
NASA JPL expresses azimuth as degrees East of North, which is
 the default representation.
NASA JPL expresses azimuth as degrees East of North which is the default representation .