add documentation for VirtualGenerator

include/htool/types/virtual_generator.hpp

@@ -6,7 +6,11 @@
 #include <iterator>
 
 namespace htool {
-
+/**
+ * @brief Define the interface for the user to give Htool a function generating dense sub-blocks of the global matrix the user wants to compress. This is done by the user implementing VirtualGenerator::copy_submatrix.
+ * 
+ * @tparam T Precision of the coefficients (float, double,...).
+ */
 template <typename T>
 class VirtualGenerator {
   protected:
@@ -18,11 +22,36 @@ class VirtualGenerator {
   public:
     VirtualGenerator(int nr0, int nc0, int dimension0 = 1) : nr(nr0), nc(nc0), dimension(dimension0) {}
 
-    // C style
+    /**
+     * @brief Generate a dense sub-block of the global matrix the user wants to compress. Note that sub-blocks queried by Htool are potentially non-contiguous in the user's numbering.
+     * 
+     * @param[in] M specifies the number of columns of the queried block
+     * @param[in] N specifies the number of rows of the queried block
+     * @param[in] rows is an integer array of size \f$M\f$. It specifies the queried columns in the user's numbering
+     * @param[in] cols is an integer array of size \f$N\f$. It specifies the queried rows in the user's numbering
+     * @param[out] ptr is a \p T precision array of size \f$ M\times N\f$. Htool already allocates and desallocates it internally, so it should **not** be allocated by the user. 
+     */
     virtual void copy_submatrix(int M, int N, const int *const rows, const int *const cols, T *ptr) const = 0;
 
+    /**
+     * @brief Get the global number of rows.
+     * 
+     * @return int 
+     */
     int nb_rows() const { return nr; }
+
+    /**
+     * @brief Get the global number of columns.
+     * 
+     * @return int 
+     */
     int nb_cols() const { return nc; }
+
+    /**
+     * @brief Get the dimension of the output coefficients.
+     * 
+     * @return int 
+     */
     int get_dimension() const { return dimension; }
 
     virtual ~VirtualGenerator(){};