NAME

liblookuptable - Look up tables in C++ using an easy to edit text format.

DESCRIPTION

This library provides operations for loading, editing, and saving look up tables. The format of the table in its text form is designed to be easy to understand and easy to edit.

Refer to the header files themselves for a specific description of the operations provided by this library. There is also a Perl version of this library available (libtext-lookuptabl-perl).

The authors inteded use of this library is to allow a user to edit a text file representation of a look up table which can then be loaded in to an embedded controller such as MegaSquirt. Additional code would be needed to convert this generic structure to whatever application specific format is required.

What is a look up table and how is it different than a table? A look up table is commonly used in embedded controllers to avoid the use of costly floating pointing operations by looking up a value based on the input coordiantes. A function with two inputs (f(x, y)) which would use floating point operations can be represented (with some loss in precsion) as a table.

In contrast a table (or spreadsheet) has any number of columns/rows. The columns can be of different types. And a table does not try to represent any sort of function, it just stores data.

STRING FORMAT

The format of the look up table when stored to a string or file should look like the example below.

                        rpm

              [1000]   [1500]  [2000]  [2500]
       [100]  14.0     15.5    16.4    17.9
  map  [90]   13.0     14.5    15.3    16.8
       [80]   12.0     13.5    14.2    15.7

The x (across top) and y (left column) coordinates have their values enclosed in square brackets. All values must be present. And the titles can only span one line. There can be any number of lines and spaces as long as the values can be discerned. When saving and restoring a table the original spacing will not be preserved.

The x values start at offset 0 at the left and increase towards the right. The y values start at offset 0 at the bottom and increase upward.

AUTHOR

Jeremiah Mahler [email protected]
http://www.google.com/profiles/jmmahler#about

COPYRIGHT

Copyright © 2011, Jeremiah Mahler. All Rights Reserved.
This project is free software and released under the GNU General Public License.