2 files changed, 19 insertions, 5 deletions

diff --git a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
index d34ee07d..c00bd33d 100644
--- a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
+++ b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
@@ -100,7 +100,7 @@ class Persistent_cohomology {
         ds_rank_(num_simplices_),                        // union-find
         ds_parent_(num_simplices_),                      // union-find
         ds_repr_(num_simplices_, NULL),                  // union-find -> annotation vectors
-        dsets_(&ds_rank_[0], &ds_parent_[0]),            // union-find
+        dsets_(ds_rank_.data(), ds_parent_.data()),      // union-find
         cam_(),                                          // collection of annotation vectors
         zero_cocycles_(),                                // union-find -> Simplex_key of creator for 0-homology
         transverse_idx_(),                               // key -> row
@@ -211,7 +211,7 @@ class Persistent_cohomology {
   /** \brief Update the cohomology groups under the insertion of an edge.
    *
    * The 0-homology is maintained with a simple Union-Find data structure, which
-   * explains the existance of a specific function of edge insertions. */
+   * explains the existence of a specific function of edge insertions. */
   void update_cohomology_groups_edge(Simplex_handle sigma) {
     Simplex_handle u, v;
     boost::tie(u, v) = cpx_->endpoints(sigma);
@@ -723,7 +723,7 @@ class Persistent_cohomology {
   boost::disjoint_sets<int *, Simplex_key *> dsets_;
   /* The compressed annotation matrix fields.*/
   Cam cam_;
-  /*  Dictionary establishing the correspondance between the Simplex_key of
+  /*  Dictionary establishing the correspondence between the Simplex_key of
    * the root vertex in the union-find ds and the Simplex_key of the vertex which
    * created the connected component as a 0-dimension homology feature.*/
   std::map<Simplex_key, Simplex_key> zero_cocycles_;
diff --git a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h
index 0673625c..f442b632 100644
--- a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h
+++ b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h
@@ -13,6 +13,7 @@
 
 #include <utility>
 #include <vector>
+#include <stdexcept>
 
 namespace Gudhi {
 
@@ -33,15 +34,28 @@ class Field_Zp {
   }
 
   void init(int charac) {
-    assert(charac > 0);  // division by zero + non negative values
     Prime = charac;
+
+    // Check that the provided prime is less than the maximum allowed as int, calculation below, and 'plus_times_equal' function : 46337 ; i.e (max_prime-1)*max_prime <= INT_MAX
+    if(Prime > 46337)
+        throw std::invalid_argument("Maximum homology_coeff_field allowed value is 46337");
+
+    // Check for primality
+    if (Prime <= 1)
+        throw std::invalid_argument("homology_coeff_field must be a prime number");
+
     inverse_.clear();
     inverse_.reserve(charac);
     inverse_.push_back(0);
     for (int i = 1; i < Prime; ++i) {
       int inv = 1;
-      while (((inv * i) % Prime) != 1)
+      int mult = inv * i;
+      while ( (mult % Prime) != 1) {
         ++inv;
+        if(mult == Prime)
+            throw std::invalid_argument("homology_coeff_field must be a prime number");
+        mult = inv * i;
+      }
       inverse_.push_back(inv);
     }
   }