 
Navigating Through the SPICE Components Hands-On Lesson (C)
===========================================================================
 
   May 21, 2018
 
 
Overview
--------------------------------------------------------
 
   In this lesson you will get familiar with the contents of and the
   documentation provided with the CSPICE Toolkit by examining the Toolkit
   directory structure, locating certain Toolkit components, running one of
   the programs provided with the Toolkit and navigating your way through
   the Toolkit documentation to answer a set of simple questions.
 
 
Note About HTML Links
--------------------------------------------------------
 
   The HTML version of this lesson contains links pointing to various HTML
   documents provided with the Toolkit. All of these links are relative
   and, in order to function, require this document to be in a certain
   location in the Toolkit HTML documentation directory tree.
 
   In order for the links to be resolved, if not done already by installing
   the lessons package under the Toolkit's ``doc/html'' directory, create a
   subdirectory called ``lessons'' under the ``doc/html'' directory of the
   ``cspice/'' tree and copy this document to that subdirectory before
   loading it into a Web browser.
 
 
References
--------------------------------------------------------
 
   Since one of the main points of this lesson is to introduce you to the
   documentation provided with the Toolkit, listing any Toolkit documents
   here will be equivalent to giving away answers. For this reason, the
   only reference document that we suggest for this lesson is the ``Intro
   to Toolkit: libraries, utilities, applications, documentation''
   tutorial. This tutorial is available from the NAIF server at JPL:
 
      http://naif.jpl.nasa.gov/naif/tutorials.html
 
 
Kernels Used
--------------------------------------------------------
 
   In this lesson you will not use any SPICE kernels.
 
 
CSPICE Modules Used
--------------------------------------------------------
 
   You also won't be required to call any CSPICE functions.
 
 
Questions
--------------------------------------------------------
 
   Instead we ask you to follow the steps below to navigate through the
   Toolkit and documentation and answer questions included in each step.
 
   Don't laugh too much if some of these questions seem really naive to
   you. We hope that answering them will help you remember better where
   various toolkit components and documents are, which in turn will make
   your SPICE learning curve a bit less steep.
 
   If you get stuck, feel free to peek at the answers provided in the
   section ``Answers'' below.
 
   If you have a printed copy of this lesson you might write down your
   answer after each question to keep track of where you are and also to
   provide a reference for subsequent programming lessons.
 
 
Step A
 
   Find the main Toolkit directory and examine its contents to answer these
   questions:
 
       1.   What is the main Toolkit directory called?
 
       2.   How many files and how many subdirectories are under it?
 
       3.   What is(are) the plain file(s) called?
 
       4.   What is(are) the subdirectory(ies) called?
 
 
Step B
 
   Examine contents of each subdirectory under the main Toolkit directory
   (using a file manager or a file list command executed from a
   command/terminal window) to answer these questions:
 
       1.   Are there any ``real'', non-cookbook data files under the
            ``data'' subdirectory?
 
       2.   Files of what types are located under the ``doc'' subdirectory?
 
       3.   What is the name of the only HTML file located under the
            ``doc/html'' subdirectory?
 
       4.   How many files and of what type are located under the ``exe''
            subdirectory?
 
       5.   How many files are under the ``lib'' subdirectory?
 
       6.   Are there any files under the ``src'' subdirectory?
 
       7.   Files of what type are located under the ``include''
            subdirectory?
 
 
Step C
 
   Find and examine the contents of the ``version.txt'' document (using a
   text editor or a file contents viewing command executed from a terminal
   window) to answer these questions:
 
       1.   What is the version of the Toolkit installed on your computer?
 
       2.   When was the Toolkit package installed on your computer
            created?
 
 
Step D
 
   Find and run the ``version'' program from a terminal/command window to
   answer this question:
 
       1.   What does the ``version'' program do when it is run without any
            command line arguments?
 
 
Step E
 
   Load the top level SPICE HTML documentation index file into an HTML
   browser of your choice and look through it to answer these questions:
 
       1.   Which link points to the document describing the Toolkit layout
            and contents?
 
       2.   Which links point to the document collections describing SPICE
            APIs?
 
       3.   Which link points to the reference documents for the SPICE
            subsystems?
 
       4.   Which link points to the documents describing programs provided
            with the toolkit?
 
       5.   How many links to pages not provided with the Toolkit are
            included in the top level index?
 
 
Step F
 
   Using the `` CSPICE API Reference Guide'' page linked from the top level
   HTML index, find and display the headers of the furnsh_c and str2et_c
   functions to answer these questions:
 
       1.   What is the purpose of the furnsh_c function stated in the
            ``Abstract'' section of the header?
 
       2.   How many arguments according to the ``I/O'' section of the
            header does the furnsh_c function have?
 
       3.   What is the name of the kernel file listed last in the
            ``Example 2'' provided in the ``Examples'' section of the
            header of the furnsh_c function?
 
       4.   Links to which documents are included in the Required_Reading
            section of the header of the str2et_c function?
 
 
Step G
 
   In the ``Most Used APIs'' page linked from the top level HTML index,
   find the section describing the function that computes the surface
   intercept point. Examine this section and the function's header linked
   from the section to answer these questions:
 
       1.   What is the name of this function?
 
       2.   How many kernels and what types are loaded by the ``Brief
            Example'' provided for this function in the ``Most Used''
            document?
 
       3.   How many examples are included in the ``Examples'' section of
            the header of this function?
 
 
Step H
 
   Using the ``Required Reading Documents'' page linked from the top level
   HTML index, find the ``Frames'' Required reading document to answer this
   question:
 
       1.   What is the ID code of the of the ``built in'' inertial
            reference frame ``ECLIPJ2000''?
 
 
Step I
 
   Using the ``Users Guides'' page linked from the top level HTML index,
   find the User's Guide for the ``version'' program. Examine it to find
   out how to run the program to display all parameters for the environment
   for which the Toolkit package was prepared. Run the program with the
   needed command line argument to answer this question:
 
       1.   For which computer type, operating system, and compiler
            combination the toolkit installed on your computer was
            prepared?
 
 
Step J
 
   Examine the ``What's New in SPICE'' document linked from the top level
   HTML index to answer these questions:
 
       1.   Which new environments were added to the set of supported
            environments with the N0061 release of the toolkit?
 
       2.   How many new applications were added to the Toolkit in the
            N0061 release of the toolkit?
 
       3.   How many bugs were fixed in the N0061 release of the toolkit?
 
 
Step K
 
   Find the files containing the source code of the ``spkezr_c'' and
   ``spkezr_'' functions and examine them to answer this question:
 
       1.   What string is used for the short error message set by the
            first argument in the ``sigerr_'' function calls?
 
 
Answers
--------------------------------------------------------
 
 
Step A
 
       1.   ``cspice''.
 
       2.   One file and seven subdirectories.
 
       3.   ``makeall.csh'' or ``makeall.bat''. This file is the script
            that rebuilds all Toolkit libraries and applications in one
            shot.
 
       4.   ``data'', ``doc'', ``etc'', ``exe'', ``include'', ``lib'', and
            ``src''. (Note that the ``etc'' subdirectory, which is usually
            empty in all generic SPICE Toolkit packages, may be absent from
            some of them.)
 
 
Step B
 
       1.   Most of the kernels provided under the ``data'' subdirectory
            are there only to support the ``cookbook'' example programs
            included in the Toolkit, as indicated by the kernel names
            staring with ``cook''. The only non-``cookbook'' file included
            in this directory -- ``geophysical.ker'' -- has an auxiliary
            purpose: it is needed by the ``mkspk'' program when it is run
            to convert two line elements (TLEs) to SPK files. NAIF strongly
            encourages users to use these kernels only for these purposes
            and not in any real applications.
 
       2.   ``.req'', ``.ug'', ``.txt'', ``.idx'', and ``.new''. The
            ``.req''s and ``.ug''s are Required Reading and User's Guide
            documents in ASCII text format. The two ``.txt''s --
            ``dscriptn.txt'' and ``version.txt'' -- are ASCII text
            documents describing the Toolkit content and version. The only
            ``.idx'' file -- ``cspice.idx'' -- is an ASCII text document
            containing CSPICE API Permuted index. The only ``.new'' --
            ``whats.new'' -- is also an ASCII text document summarizing
            additions and changes for each released version of the Toolkit.
 
       3.   ``index.html''. This file is the top level index for the HTML
            documentation provided with the Toolkit.
 
       4.   17 files (in Toolkit version N0061). All of these files are
            executables.
 
       5.   Two: the main CSPICE library ``cspice'', and the library
            containing routines supporting some of the Toolkit applications
            ``csupport''. (The library file name extensions vary depending
            on platform.)
 
       6.   No. The ``src'' subdirectory contains only subdirectories with
            the source code for the libraries and programs provided in the
            Toolkit.
 
       7.   The ``include'' subdirectory contains CSPICE C header files.
 
 
Step C
 
       1.   ``N0063'' (if you have the latest Toolkit as of 02/19/10).
 
       2.   ``April 16, 2009'' (if you have the latest Toolkit as of
            02/19/10).
 
 
Step D
 
       1.   The program prints to the screen five characters indicating the
            Toolkit version -- ``N0063'' (if you have the latest Toolkit as
            of 02/19/10).
 
 
Step E
 
       1.   `` CSPICE Toolkit Contents''.
 
       2.   ``Most Used CSPICE APIs'', `` CSPICE API Reference Guide'' and
            `` CSPICE API Permuted Index''.
 
       3.   ``Required Reading Documents''.
 
       4.   ``User's Guides''.
 
       5.   One: the link to the NAIF Web site at the bottom of the page.
 
 
Step F
 
       1.   To load one or more SPICE kernels into a program.
 
       2.   One: the name of a kernel or meta-kernel to be loaded.
 
       3.   ``/home/mydir/kernels/ck/c-kernel.bc''.
 
       4.   ``TIME'' Required Reading.
 
 
Step G
 
       1.   ``sincpt_c''.
 
       2.   Eight: an LSK, a PCK, an SCLK, two SPKs, a CK, an FK, and an
            IK.
 
       3.   Two.
 
 
Step H
 
       1.   17. It is specified in the section ``Appendix. ``Built in''
            Inertial Reference Frames.''
 
 
Step I
 
       1.   The answer will vary depending on the Toolkit package installed
            on your system. For a N0063 PC/Linux/G77 package, for example,
            the program output will look like this:
 
               % toolkit/exe/version -a
 
               Toolkit version  : N0061
               System           : PC
               Operating System : LINUX
               Compiler         : G77
               File Format      : LTL-IEEE
               Text File Format : LF
               MAX DP           :  1.7976931348623E+308
               MIN DP           : -1.7976931348623E+308
               MAX INT          :  2147483647
               MIN INT          : -2147483647
 
 
 
Step J
 
       1.   The following five new environments were added in the N0061
            release of the Toolkit:
 
              FORTRAN Toolkit:
                 Mac/Intel    OS-X          Intel FORTRAN
                 PC           Windows       Intel FORTRAN
              CSPICE:
                 Mac/Intel    OS-X          Apple C
                 Sun          Solaris       gCC/64bit
              ICY:
                 Mac/Intel    OS-X          Apple C / IDL 6.3
 
       2.   Two: ``MSOPCK'' and ``SPKDIFF''.
 
       3.   Eleven. This number is greater than the number of subsections
            under the ``Bug Fixes'' section because more than one bug was
            fixed in some of the routines and programs listed there.
 
 
Step K
 
       1.   Both calls to ``sigerr_'' in ``spkezr_'' set the short error
            message to 'SPICE(IDCODENOTFOUND)'. To determine this you need
            to load the ``spkezr_'' source code file
            ``cspice/src/cspice/spkezr.c'' into a text editor and search it
            for calls for ``sigerr_''. Note that examining the ``spkezr_c''
            source code file ``cspice/src/cspice/spkezr_c.c'' will not
            answer this question because ``spkezr_c'' is a wrapper that
            simply calls ``spkezr_'' generated by ``f2c'' from the SPICE
            FORTRAN routine ``SPKEZR''.
 
