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 * Discovered a serious fencepost error in loops.
   * Temporary solution: allocate one more memory spot than necessary to allow Leon's indexing
   * Long term: correct all of Leon's loops to index properly.
 * Discovered undocumented restriction on Cayley library names: no hyphens.

[:reu07: Back to the REU wiki]

J.S. Leon's [http://tigger.uic.edu/~jleon/ webpage]

Goals

  • Fix up Leon's code for modern use.

Progress

  • Fixed several issues relating to outdated design.
    • Originally defaulted to using short's: now uses unsigned's.
    • Changed obsolete CLK_TCK to CLOCKS_PER_SEC.
  • Discovered a serious fencepost error in loops.
    • Temporary solution: allocate one more memory spot than necessary to allow Leon's indexing
    • Long term: correct all of Leon's loops to index properly.
  • Discovered undocumented restriction on Cayley library names: no hyphens.

Solutions to known bugs

  1. Related to reading the input file:
    • ./wtdist huffman-code4.gap 6 huffman-matrix4 // seems to work, creates huffman-matrix4 file
      ./desauto -code huffman-code4.gap huffman-matrix4 huffman-autgp4 // does not work
      
      output:
      Error: Library block huffman-matrix4 not found in specified library.
      Program was executing function read01Matrix (line 234 in file
      ../../src/leon/src/readdes.c).
    • Related files:
      • attachment:huffman-code4.gap
    • SOLUTION: Cayley library format does not support names with hyphens. Use only alphanumeric and underscore characters.

Known Bugs in Leon

  1. Running out of memory:
    • W. C. Huffman describes a general procedure to produce examples of this bug:
      The main problem always seems to be when there are only a few minimal weight codewords.  I think you can create a lot of examples that will make it difficult in the following way: Let C1 be any code you want with minimum weight at least 3. Let C2 be the [2,1,2] code with basis [1 1].  Form the direct sum of C1 and C2.  This will create a code of minimum weight 2 with only one codeword of minimum weight 2.  I have a feeling this will give you trouble even if the code C1 has an automorphism group that is easy to compute.
    • The following codes commonly cause an out of memory condition. Even if this doesn't happen, they are still good benchmarks for memory use:
      Example 1:
      1111111111110000000000001100000000
      0000000000001010100000000010101011
      0000000000000101010000000001010111
      0000000000000000001010100000001110
      0000000000000000000101010000001101
      0000001010101010100000001000100000
      0000000101010101010000000100010000
      1010100000001010100000001010000000
      0101010000000101010000000101000000
      0010100000000010100011110000000000
      0001010000000001010011110000000000
      1000100000001000101100110000000000
      0100010000000100011100110000000000
      0000000010100011110010100000000000
      0000000001010011110001010000000000
      0000001000101100111000100000000000
      0000000100011100110100010000000000
      
      Example 2:
      1111111111110000000000001100000000
      0000000000001010100000000010101011
      0000000000000101010000000001010111
      0000000000000000001010100000001110
      0000000000000000000101010000001101
      0000001010101010100000001000100000
      0000000101010101010000000100010000
      1010100000001010100000001010000000
      0101010000000101010000000101000000
      0010100000000010100011110000000000
      0001010000000001010011110000000000
      1000100000001000101100110000000000
      0100010000000100011100110000000000
      0000000010100011110001010000000000
      0000000001010011110010100000000000
      0000001000101100110100010000000000
      0000000100011100111000100000000000
      
      Example 3:
      1111111111110000000000001100000000
      0000000000000000001111110010101010
      0000000000000000001111110001010101
      0000000000001010101010100000000011
      0000000000000101010101010000000011
      0000001010100000000000001000101000
      0000000101010000000000000100010100
      1010100000000000000000001010001000
      0101010000000000000000000101000100
      0010100000000010100011110000000000
      0001010000000001010011110000000000
      1000100000001000101100110000000000
      0100010000000100011100110000000000
      0000000010100011110010100000000000
      0000000001010011110001010000000000
      0000001000101100111000100000000000
      0000000100011100110100010000000000
      
      Example 4:
      1111111111110000000000001100000000
      0000000000000000001111110010101010
      0000000000000000001111110001010101
      0000000000001010101010100000000011
      0000000000000101010101010000000011
      0000001010100000000000001000101000
      0000000101010000000000000100010100
      1010100000000000000000001010001000
      0101010000000000000000000101000100
      0010100000000001010011110000000000
      0001010000000010100011110000000000
      1000100000000100011100110000000000
      0100010000001000101100110000000000
      0000000010100011110001010000000000
      0000000001010011110010100000000000
      0000001000101100110100010000000000
      0000000100011100111000100000000000
  2. Bus Errors
    • ./wtdist example1::left 4 really
      Bus error
    • Related file:
      • attachment:example1
    • Happens on OS X, but not Linux.

Leon (last edited 2008-11-14 13:42:10 by localhost)