INDEX
Indexing Multidimensional Arrays

INDEX is a MATLAB library which can convert the index of a multidimensional array entry into the corresponding index of a one dimensional vector, using either row or column major indexing, with zero or unit base.

2D Array Example:

Consider, for example, the following 3x4 array A:

        11 12 13 14
        21 22 23 24
        31 32 33 34
      

Indexing by columns, the array would be stored in a 1D vector as

        11 21 31 | 12 22 32 | 13 23 33 | 14 24 34
      

        11 21 31 | 12 22 32 | 13 23 33 | 14 24 34
         0  1  2    3  4  5    6  7  8    9 10 11  <- zero based
         1  2  3    4  5  6    7  8  9   10 11 12  <- one based
      

Indexing by rows, the array would be stored in a 1D vector as

        11 12 13 14 | 21 22 23 24 | 31 32 33 34
      

        11 12 13 14 | 21 22 23 24 | 31 32 33 34
         0  1  2  3    4  5  6  7   8   9 10 11  <- zero based
         1  2  3  4    5  6  7  8   9  10 11 12  <- one based
      

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

INDEX is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

CELL, a MATLAB library which defines a cell array, a generalization of an array which can compactly store and retrieve vector or matrix data of varying size, such as the rows of a triangular matrix.

SUBPAK, a MATLAB library which contains many utility routines;

Source Code:

• index0.m, indexes a 1D vector using a zero base.
• index01.m, indexes a 2D array by columns, with a zero base.
• index012.m, indexes a 3D array by columns with zero base.
• index0123.m, indexes a 4D array by columns, with a zero base.
• index0n.m, indexes an N-dimensional array by columns, with zero base.
• index1.m, indexes a 1D vector using a unit base.
• index10.m, indexes a 2D array by rows, with a zero base.
• index12.m, indexes a 2D array by columns, with a unit base.
• index123.m, indexes a 3D array by columns with unit base.
• index1234.m, indexes a 4D array by columns, with a unit base.
• index1n.m, indexes an N-dimensional array by columns, with unit base.
• index21.m, indexes a 2D array by rows, with a unit base.
• index210.m, indexes a 3D array by rows, with zero base.
• index321.m, indexes a 3D array by rows, with zero base.
• index3210.m, indexes a 4D array by rows, with zero base.
• index4321.m, indexes a 4D array by rows, with unit base.
• indexn0.m, indexes an N-dimensional array by rows, with zero base.
• indexn1.m, indexes an N-dimensional array by rows, with unit base.
• timestamp.m, prints the current YMDHMS date as a time stamp.

Examples and Tests:

• index_test.m, a sample calling program.
• index_test01.m, tests INDEX0 and INDEX1.
• index_test02.m, tests INDEX01, INDEX10, INDEX12 and INDEX21.
• index_test03.m, tests INDEX012, INDEX123, INDEX210, and INDEX321.
• index_test04.m, tests INDEX0123, INDEX1234, INDEX3210, and INDEX4321.
• index_test05.m, tests INDEX0N, INDEX1N, INDEXN0 and INDEXN1.
• index_test_output.txt, the output file.

You can go up one level to the MATLAB source codes.