Library interface

A simple example program

The following example program shows the typical usage of the Fortran 2003 interface.

Other examples using the Fortran 2003 interface can be found in the directory examples of the library sources.

program f2003multiple
    USE, INTRINSIC :: ISO_C_BINDING
    use calceph
    integer res
    real(8) AU
    TYPE(C_PTR) :: peph

    peph = calceph_open("example1.dat"//C_NULL_CHAR)
    if (C_ASSOCIATED(peph)) then

       if (calceph_getconstant(peph, "AU"//C_NULL_CHAR, AU).eq.1) then
            write (*,*) "AU=", AU
       endif

       call calceph_close(peph)
     endif
stop
end

Modules and Libraries

All declarations needed to use CALCEPH Library are collected in the module files calceph.mod. The library is designed to work with Fortran compilers compliant with the Fortran 2003 standard. All declarations use the standard ISO_C_BINDING module.

You should include that module in any program using the CALCEPH library:

use calceph

When a fortran string is given as a parameter to a function of this library, you should append this string with //C_NULL_CHAR because the C library works only with C string.

Compilation on a Unix-like system

All programs using CALCEPH must link against the libcalceph library. On Unix-like system this can be done with -lcalceph, for example

gfortran -I/usr/local/include myprogram.f -o myprogram -lcalceph

If CALCEPH Library has been installed to a non-standard location then it may be necessary to use -I and -L compiler options to point to the right directories, and some sort of run-time path for a shared library.

Compilation on a Windows system

All programs using CALCEPH must link against the libcalceph.lib. On Windows system this can be done with libcalceph.lib, for example

gfortran.exe /out:myprogram.exe myprogram.f libcalceph.lib

If CALCEPH Library has been installed to a non-standard location then it may be necessary to use /I and /LIBPATH: compiler options to point to the right directories.

Types

Constants

The following constants are defined in the module calceph.mod.

CALCEPH_MAX_CONSTANTNAME [integer]

This integer defines the maximum number of characters, including the trailing '\0', that the name of a constant, available from the ephemeris file, could contain.

CALCEPH_MAX_CONSTANTVALUE [integer]

This integer defines the maximum number of characters, including the trailing '\0', that the value of a constant, available from the ephemeris file, could contain if the value is stored as a string of characters.

CALCEPH_VERSION_MAJOR [integer]

This integer constant defines the major revision of this library. It can be used to distinguish different releases of this library.

CALCEPH_VERSION_MINOR [integer]

This integer constant defines the minor revision of this library. It can be used to distinguish different releases of this library.

CALCEPH_VERSION_PATCH [integer]

This integer constant defines the patch level revision of this library. It can be used to distinguish different releases of this library.

CALCEPH_VERSION_STRING [character(len=*)]

This string is the version of the library, which can be compared to the result of calceph_getversion to check at run time if the header file and library used match:

Note: Obtaining different strings is not necessarily an error, as in general, a program compiled with some old CALCEPH version can be dynamically linked with a newer CALCEPH library version (if allowed by the operating system).

CALCEPH_ASTEROID [integer]

This integer defines the offset value for the asteroids that must be used as target or center for the computation functions, such as calceph_compute().

The following constants specify in which units are expressed the output of the computation functions, such as calceph_compute_unit() :

CALCEPH_UNIT_AU [integer]

This integer defines that the unit of the positions and velocities is expressed in astronomical unit.

CALCEPH_UNIT_KM [integer]

This integer defines that the unit of the positions and velocities is expressed in kilometer.

CALCEPH_UNIT_DAY [integer]

This integer defines that the unit of the velocities or the quantity TT-TDB or TCG-TCB is expressed in day (one day=86400 seconds).

CALCEPH_UNIT_SEC [integer]

This integer defines that the unit of the velocities or the quantity TT-TDB or TCG-TCB is expressed in second.

CALCEPH_UNIT_RAD [integer]

This integer defines that the unit of the angles is expressed in radian.

CALCEPH_OUTPUT_EULERANGLES [integer]

This integer defines that the output array contains the euler angles.

CALCEPH_OUTPUT_NUTATIONANGLES [integer]

This integer defines that the output array contains the nutation angles.

CALCEPH_USE_NAIFID [integer]

This integer defines that the NAIF identification numbers are used as target or center for the computation functions, such as calceph_compute_unit().

The following constants specify the type of segments for the functions, such as calceph_getmaxsupportedorder() :

CALCEPH_SEGTYPE_ORIG_0 [integer]

This integer defines the type of segment for the original INPOP/JPL DE file format.

CALCEPH_SEGTYPE_SPK_1 [integer]

CALCEPH_SEGTYPE_SPK_2 [integer]

CALCEPH_SEGTYPE_SPK_3 [integer]

CALCEPH_SEGTYPE_SPK_5 [integer]

CALCEPH_SEGTYPE_SPK_8 [integer]

CALCEPH_SEGTYPE_SPK_9 [integer]

CALCEPH_SEGTYPE_SPK_12 [integer]

CALCEPH_SEGTYPE_SPK_13 [integer]

CALCEPH_SEGTYPE_SPK_14 [integer]

CALCEPH_SEGTYPE_SPK_17 [integer]

CALCEPH_SEGTYPE_SPK_18 [integer]

CALCEPH_SEGTYPE_SPK_19 [integer]

CALCEPH_SEGTYPE_SPK_20 [integer]

CALCEPH_SEGTYPE_SPK_21 [integer]

CALCEPH_SEGTYPE_SPK_102 [integer]

CALCEPH_SEGTYPE_SPK_103 [integer]

CALCEPH_SEGTYPE_SPK_120 [integer]

This integer defines the type of segments (1, 2, 3, 5, 8, 9, 12, 13, 14, 17, 18, 20, 21, 102, 103 and 120) for the SPICE Kernel files.