libred_solar_elevation.3

.TH LIBRED_SOLAR_ELEVATION 3 LIBRED
.SH NAME
libred_solar_elevation \- Calculate the Sun's apparent elevation
.SH SYNOPSIS
.nf
#include <libred.h>

int \fBlibred_solar_elevation\fP(double \fIlatitude\fP, double \fIlongitude\fP, double *\felevation\fP);
.fi
.PP
Link with
.IR -lred .
.SH DESCRIPTION
.BR libred_solar_elevation ()
calculates the Sun's elevation, and stores it, measured in degrees, in
.IR *elevation ,
as apparent from a selected geographical position, namely from
.I latitude
degrees north of GPS's equator and
.I longitude
degrees east of GPS's prime meridian. The function is only
explicitly defined for values between -90 and +90 for
.I latitude
and values between -180 and +180 for and
.IR longitude .
Other values may or may not work, no error is thrown if used.
.SH RETURN VALUE
Upon successful completion, the 
.BR libred_solar_elevation ()
return 0, on failure it returns -1 and sets
.I errno
to indicate the error.
.SH ERRORS
The function may fail for any reason specified for
.BR clock_gettime (3).
.SH SEE ALSO
.BR libred.h (0),
.BR libred (7),
.BR libred_check_timetravel (3),
.BR libred_get_colour (3)