* Kingston - Canada
* Changes :
* - Internal convention : zeros are no longer stored in memory. All functions were changed to reflect this. This is transparent to users.
* - Performance improvements for large sparse matrices (based on above), mostly for multiplication and inversion.
* - Four new functions : utrig, ltrig, diag and smooth :
* upper triangular matrix, lower triangular matrix, diagonal matrix and smooth small number to zero (see documentation).
* - Correction of numerous bugs.
*
* Modified : 10/Nov/2009
* Pier-André Bouchard St-Amant pabsta [at] econ.queensu.ca
* Kingston - Canada
* - Changes :
* 1) (Almost) all function specs so that inputs are matrix objects.
* 2) Deletion of five functions (including some "statistical" ones) and two global variables
* 3) Introduction of nine new "basic" functions
* - get_data, get_value, set_value, get_columns, get_rows, set_columns, set_rows, delete_columns, delete_rows
* - print_matrix (mostly for debugging purpose, as it prints a )
* 4) Introduction of eleven new mathematical functions :
* - point to point product and division.
* - eye (identity matrix), ones (matrix of ones), zeros (matrix of zeros) and random matrix "quasi-constructors"
* - max, min of a column
* - point to point greater than, greater or equal than, smaller than, smaller or equal, equal
* 5) Correction of numerous bugs.
* 6) Translation of spanish to english, identation and uniformisation of the function names
*
* - Comments :
* a) All mathematical functions are written to ressemble paper algebra :
* - AxB ==> $A->times($B);
* - A-B ==> $A->minus($B);
* - A^(-1) ==> $A->inv();
* - A' ==> $A->prime();
* - det(A) ==> $A->det($A);
* - etc.
* This restricts nested calls, but augment readability.
* b) The algorithm for matrix inversion is based on PLU decomposition. The algorithm performs relatively well numerically, but it requires an order of 2*n^2 x sizeof(doubles) of memory space.
* c) Error messages are echoed to the standard output (likely to be your webpage)
*
* A class for operations on matrices
* Creation date: 30/sept/2005
* Diego Carrera - Kleber BaÒo
* Guayaquil - Ecuador (Spanish version)
*/
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