Mikael Johansson on Tue, 02 Mar 2004 13:08:12 +0100 |
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Matrix initialization in Library mode |
For a homology calculation application I am building, I need to calculate matrix ranks over any characteristic. I decided that the Pari library seems to help me do just this, and so started my coding and construction. Now I've reached the point where I need to start involving the Pari library, and promptly run into slight problems. I need to initialize a (probably rather sparse) matrix with entries in {-1, 0, 1} for use with either the keri or ker_mod_p library calls. The users guide gives in section 4.3 an example on how to create a matrix by using the cgetg command recursively - first for the root, and then for the columns of the matrix; but on the other hand, the entries in section 4.5 specifying the handling of t_MAT and t_COL state that these are introduced for specific GP use and recommend that one uses standard malloced C matrices when programming in library mode. Is there a way to build the matrix in malloced memory and then introduce it to Pari for use of the rank calculation functions? Or should I ignore the comment in section 4.5? The code example with cgetg allocated 4 t_COLs of size 5 as the initialization for a 4x3 matrix - why 5? I obviously miss certain parts of the programming philosophy, and await enlightenment hopefully. -- Mikael Johansson | To see the world in a grain of sand mik@math.su.se | And heaven in a wild flower | To hold infinity in the palm of your hand | And eternity for an hour