Main Page Navigating Through the SPICE Components Hands-On Lesson (Python)
## Table of Contents
       Navigating Through the SPICE Components Hands-On Lesson (Python)
          Note to SpiceyPy Users
          Overview
          Note About HTML Links
          References
          Kernels Used
          SpiceyPy Modules Used
          Questions
             Step A
             Step B
             Step C
             Step D
             Step E
             Step F
             Step G
             Step H
             Step I
             Step J
             Step K
          Answers
             Step A
             Step B
             Step C
             Step D
             Step E
             Step F
             Step G
             Step H
             Step I
             Step J
             Step K
Top # Navigating Through the SPICE Components Hands-On Lesson (Python) May 21, 2018 Top ## Note to SpiceyPy Users SpiceyPy users are encouraged to install a CSPICE toolkit to make SPICE toolkit applications and complete SPICE documentation, which are not included in SpiceyPy, available on their computer. To help them navigate through the CSPICE Toolkit this lesson introduces its structure and contents. Top ## 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. Top ## 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. Top ## 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
Top ## Kernels Used In this lesson you will not use any SPICE kernels. Top ## SpiceyPy Modules Used You also won't be required to call any SpiceyPy functions. Top ## 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. Top ### 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? Top ### 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? Top ### 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? Top ### 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? Top ### 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? Top ### 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? Top ### 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? Top ### 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''? Top ### 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? Top ### 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? Top ### 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? Top ## Answers Top ### 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.) Top ### 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. Top ### 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). Top ### 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). Top ### 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. Top ### 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. Top ### Step G `1.` ``sincpt_c''. `2.` Eight: an LSK, a PCK, an SCLK, two SPKs, a CK, an FK, and an IK. `3.` Two. Top ### Step H `1.` 17. It is specified in the section ``Appendix. ``Built in'' Inertial Reference Frames.'' Top ### 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
Top ### 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. Top ### 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''.