small changes

src/Persistence_matrix/doc/Intro_field_elements_and_operators.h

@@ -25,7 +25,7 @@ namespace persistence_fields {
  * There are two types of classes:
  * - those defining directly a field element, allowing to use them as any integer: the operators are overwritten such
  *   that the calculation is done in the field. For example, if \f$ e = 2 \f$ is an instanciation of an
- *   \f$ \mathbb{F}_3 \f$ element class, then `e + 3` returns `2`,
+ *   \f$ \mathbb{F}_3 \f$ element class, then `e + 3` returns an element instanciation of value `2`,
  * - those only defining the operators of a field or multi-field. They represent a collection of methods taking
  *   one or two integers as input and treating them as elements of the field. For example, if \f$ op \f$ is an
  *   instanciation of a \f$ \mathbb{F}_3 \f$ operator class, `op.add(2, 3)` returns `2`.

src/Persistence_matrix/example/simplex_tree_to_matrix.cpp

@@ -131,7 +131,7 @@ int main() {
     for (auto b : st.boundary_simplex_range(sh)){
       boundary.push_back(st.key(b));
     }
-    std::sort(boundary.begin(), boundary.end());  //boundaries have to ordered
+    std::sort(boundary.begin(), boundary.end());  //boundaries have to be ordered
 
     //insertion in the matrices, the id is continuously increasing from 0 so no need to give it as an argument.
     bm.insert_boundary(boundary);

src/Persistence_matrix/include/gudhi/Persistence_matrix/base_pairing.h

@@ -147,8 +147,8 @@ inline void Base_pairing<Master_matrix>::_reduce()
     columnsByDim[dim - _matrix()->get_column_dimension(i)].push_back(i);
   }
 
-  for (auto cols : columnsByDim) {
-    for (auto i : cols) {
+  for (const auto& cols : columnsByDim) {
+    for (index i : cols) {
       auto& curr = _matrix()->get_column(i);
       if (curr.is_empty()) {
         if (pivotsToColumn.find(i) == pivotsToColumn.end()) {

src/Persistence_matrix/include/gudhi/matrix.h

@@ -28,6 +28,8 @@
 
 #include <gudhi/persistence_matrix_options.h>
 
+#include <gudhi/Fields/Z2_field_operators.h>
+
 #include <gudhi/Persistence_matrix/overlay_ididx_to_matidx.h>
 #include <gudhi/Persistence_matrix/overlay_posidx_to_matidx.h>
 
@@ -146,37 +148,30 @@ class Matrix {
   using pos_index = typename PersistenceMatrixOptions::index_type;             /**< Type of @ref PosIdx index. */
   using dimension_type = typename PersistenceMatrixOptions::dimension_type;    /**< Type for dimension value. */
 
-  struct Dummy_field_operators{
-    using element_type = unsigned int;
-    using characteristic_type = element_type;
+  // struct Dummy_field_operators{
+  //   using element_type = unsigned int;
+  //   using characteristic_type = element_type;
 
-    Dummy_field_operators([[maybe_unused]] characteristic_type characteristic = 0){}
+  //   Dummy_field_operators([[maybe_unused]] characteristic_type characteristic = 0){}
 
-    friend void swap([[maybe_unused]] Dummy_field_operators& d1, [[maybe_unused]] Dummy_field_operators& d2){}
+  //   friend void swap([[maybe_unused]] Dummy_field_operators& d1, [[maybe_unused]] Dummy_field_operators& d2){}
 
-    static constexpr characteristic_type get_characteristic() { return 2; }
-  };
+  //   static constexpr characteristic_type get_characteristic() { return 2; }
+  // };
 
   /**
    * @brief Coefficiants field type.
    */
   using Field_operators =
       typename std::conditional<PersistenceMatrixOptions::is_z2, 
-                                Dummy_field_operators, 
+                                Gudhi::persistence_fields::Z2_field_operators, 
                                 typename PersistenceMatrixOptions::Field_coeff_operators
                                >::type;
   /**
    * @brief Type of a field element.
    */
-  using element_type = typename std::conditional<PersistenceMatrixOptions::is_z2, 
-                                                 bool, 
-                                                 typename Field_operators::element_type
-                                                >::type;
-  using characteristic_type =
-      typename std::conditional<PersistenceMatrixOptions::is_z2, 
-                                unsigned int, 
-                                typename Field_operators::characteristic_type
-                               >::type;
+  using element_type = typename Field_operators::element_type;
+  using characteristic_type = typename Field_operators::characteristic_type;
 
   // TODO: move outside? unify with other bar types in Gudhi?
   /**