3.1.2 CloogMatrix

The CloogMatrix structure is equivalent to the PolyLib Matrix data structure (see Wil93). This structure is devoted to represent a set of constraints.

struct cloogmatrix
{ unsigned NbRows ;    /* Number of rows. */
  unsigned NbColumns ; /* Number of columns. */
  cloog_int_t **p;     /* Array of pointers to the matrix rows. */
  cloog_int_t *p_Init; /* Matrix rows contiguously in memory. */
};
typedef struct cloogmatrix CloogMatrix;

CloogMatrix *cloog_matrix_alloc(unsigned NbRows, unsigned NbColumns);
void cloog_matrix_print(FILE *foo, CloogMatrix *m);
void cloog_matrix_free(CloogMatrix *matrix);

The whole matrix is stored in memory row after row at the p_Init address. p is an array of pointers where p[i] points to the first element of the i^{th} row. NbRows and NbColumns are respectively the number of rows and columns of the matrix. Each row corresponds to a constraint. The first element of each row is an equality/inequality tag. The constraint is an equality p(x) = 0 if the first element is 0, but it is an inequality p(x) \geq 0 if the first element is 1. The next elements are the coefficients of the unknowns, followed by the coefficients of the parameters, and finally the constant term. For instance, the following three constraints:

    -i + m  = 0
    -j + n >= 0
 i + j - k >= 0

would be represented by the following rows:

# eq/in  i   j   k   m   n   cst
    0    0  -1   0   1   0    0 
    1   -1   0   0   0   1    0 
    1    1   1  -1   0   0    0 

To be able to provide different precision version (CLooG supports 32 bits, 64 bits and arbitrary precision through the GMP library), the cloog_int_t type depends on the configuration options (it may be long int for 32 bits version, long long int for 64 bits version, and mpz_t for multiple precision version).

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