Using the HEALPix IDL facilities

The current version of the HEALPix package provides an IDL startup file which defines various environment variables for your convenience, and adds the HEALPix IDL directory tree to your IDL_PATH. In order to utilise this feature, the user should invoke IDL using the commands hidl or hidlde which are aliases defined in the HEALPix profile created during the installation process for the package (see the Installation Document).

Using HEALPix IDL together with other IDL libraries

Many users want to use HEALPix IDL routines at the same time as other (home made or third party) IDL routines. There are several ways to achieve this:
- with hidl:
before starting hidl or hidlde, (re)define the environment variable $IDL_PATH so that it looks like: ``+/path/to/my/idl/routines:+/path/to/other/idl/routines:<IDL_DEFAULT>'' (where <IDL_DEFAULT> should be typed literally and the +/path means that subdirectories of path will be searched recursively). For example, if young Albert types in Bourne shell:
export IDL_PATH=``+/home/aeinstein/brownian:<IDL_DEFAULT>''
he will start an IDL session in which the HEALPix IDL routines are accessible, followed by all those located in subdirectories of /home/aeinstein/brownian, followed by the standard IDL routines. If .pro files of the same name are avaible at the different locations, the first one encountered will prevail;
- without hidl:
before starting IDL, the environment variables $IDL_PATH and $IDL_STARTUP must be defined. For instance, to emulate under (ba)sh the behavior of hidl shown above, the same (bolder) Albert will type:
export IDL_PATH=``+${HEALPIX}/src/idl:+/home/aeinstein/brownian:<IDL_DEFAULT>''
export IDL_STARTUP=``+${HEALPIX}/src/idl/HEALPix_startup''

GDL users can do the same, replacing hidl, IDL_PATH and IDL_STARTUP with hgdl, GDL_PATH and GDL_STARTUP respectively, while <IDL_DEFAULT> must be replaced by the default value of ${GDL_PATH}.
Of course, ${HEALPIX}/src/idl (and all the + signs) remain unchanged.

Using GDL instead of IDL

See the section ``Using GDL instead of IDL'' in the Installation Document for more information on this issue.

Version 3.31, 2017-01-06