Various commonly used routines used throughout the SuperNOVAS library. More...

Functions
double	d_light (const double pos_src, const double pos_body)
	Returns the difference in light-time, for a star, between the barycenter of the solar system and the observer (or the geocenter) (Usage A).

PROTECTED void	novas_debug (enum novas_debug_mode mode)
	Enables or disables reporting errors and traces to the standard error stream.

double	novas_equ_sep (double ra1, double dec1, double ra2, double dec2)
	Returns the angular separation of two equatorial locations on a sphere.

enum novas_debug_mode	novas_get_debug_mode ()
	Returns the current, thread-local, mode for reporting errors encountered (and traces).

double	novas_norm_ang (double angle)
	Returns the normalized angle in the [0:2π) range.

int	novas_print_dms (double degrees, enum novas_separator_type sep, int decimals, char *restrict buf, int len)
	Prints an angle in degrees as [-]ddd:mm:ss[.S...] into the specified buffer, with up to nanosecond precision.

int	novas_print_hms (double hours, enum novas_separator_type sep, int decimals, char *restrict buf, int len)
	Prints a time in hours as hh:mm:ss[.S...] into the specified buffer, with up to nanosecond precision.

double	novas_sep (double lon1, double lat1, double lon2, double lat2)
	Returns the angular separation of two locations on a sphere.

double	novas_vlen (const double *restrict v)
	(for internal use only) Calculates the length of a 3-vector

int	radec2vector (double ra, double dec, double dist, double *restrict pos)
	Converts equatorial spherical coordinates to a vector (equatorial rectangular coordinates).

int	spin (double angle, const double in, double out)
	Transforms a vector from one coordinate system to another with same origin and axes rotated about the z-axis.

short	vector2radec (const double restrict pos, double restrict ra, double *restrict dec)
	Converts an vector in equatorial rectangular coordinates to equatorial spherical coordinates.

Variables
int	novas_inv_max_iter = 100
	Maximum number of iterations for convergent inverse calculations.

Detailed Description

Various commonly used routines used throughout the SuperNOVAS library.

Date: Created on Mar 6, 2025

Author: G. Kaplan and Attila Kovacs

Function Documentation

◆ d_light()

double d_light	(	const double *	pos_src,
		const double *	pos_body )

Returns the difference in light-time, for a star, between the barycenter of the solar system and the observer (or the geocenter) (Usage A).

Alternatively (Usage B), this function returns the light-time from the observer (or the geocenter) to a point on a light ray that is closest to a specific solar system body. For this purpose, 'pos_src' is the position vector toward observed object, with respect to origin at observer (or the geocenter); 'pos_body' is the position vector of solar system body, with respect to origin at observer (or the geocenter), components in AU; and the returned value is the light time to point on line defined by 'pos' that is closest to solar system body (positive if light passes body before hitting observer, i.e., if 'pos_body' is within 90 degrees of 'pos_src').

NOTES:

This function is called by novas_geom_posvel(), novas_sky_pos(), or place()

Parameters

pos_src	Position vector towards observed object, with respect to the SSB (Usage A), or relative to the observer / geocenter (Usage B).
pos_body	[AU] Position of observer relative to SSB (Usage A), or position of intermediate solar-system body with respect to the observer / geocenter (Usage B).

Returns: [day] Difference in light time to observer, either relative to SSB (Usage A) or relative intermediate solar-system body (Usage B); or else NAN if either of the input arguments is NULL.

See also: novas_sky_pos(), novas_geom_posvel()

References novas_vlen().

◆ novas_vlen()

double novas_vlen ( const double *restrict v )

(for internal use only) Calculates the length of a 3-vector

Parameters

v	Pointer to a 3-component (x, y, z) vector. The argument cannot be NULL

Returns: the length of the vector

Since: 1.0

Author: Attila Kovacs

See also: novas_vdot(), novas_vdist()

Variable Documentation

◆ novas_inv_max_iter

int novas_inv_max_iter = 100

Maximum number of iterations for convergent inverse calculations.

Most iterative inverse functions should normally converge in a handful of iterations. In some pathological cases more iterations may be required. This variable sets an absolute maximum for the number of iterations in order to avoid runaway (zombie) behaviour. If inverse functions fail to converge, they will return a value indicating an error, and errno should be set to ECANCELED.

Since: 1.1