Remove unnecessary checks for primality

Document homology_coeff_field values in cubical

2 files changed, 7 insertions, 6 deletions

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 7ecc9a80..8ec89e41 100644
--- a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h
+++ b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology/Field_Zp.h
@@ -38,12 +38,12 @@ class Field_Zp {
 
     Prime = charac;
 
-    // Check that the provided prime is less than the maximum allowed as int and calculation below : 46337 ; i.e (max_prime-1)**2 <= INT_MAX
+    // 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 == 0) || (Prime == 1) || ((Prime > 3) && ((Prime % 2 == 0) || (Prime % 3 == 0))))
+    if (Prime <= 1)
         throw std::invalid_argument("homology_coeff_field must be a prime number");
 
     inverse_.clear();
@@ -59,10 +59,6 @@ class Field_Zp {
         mult = inv * i;
       }
       inverse_.push_back(inv);
-      if ( (i*i <= Prime) && (((i-5)%6) == 0) ) {
-        if ((Prime % i == 0) || (Prime % (i + 2) == 0))
-            throw std::invalid_argument("homology_coeff_field must be a prime number");
-      }
     }
   }
 
diff --git a/src/Persistent_cohomology/test/persistent_cohomology_unit_test.cpp b/src/Persistent_cohomology/test/persistent_cohomology_unit_test.cpp
index 35bb5988..041cb0fd 100644
--- a/src/Persistent_cohomology/test/persistent_cohomology_unit_test.cpp
+++ b/src/Persistent_cohomology/test/persistent_cohomology_unit_test.cpp
@@ -176,6 +176,11 @@ BOOST_AUTO_TEST_CASE( rips_persistent_cohomology_single_field_dim_5 )
   test_rips_persistence_in_dimension(5);
 }
 
+BOOST_AUTO_TEST_CASE( rips_persistent_cohomology_single_field_dim_6 )
+{
+  BOOST_CHECK_THROW(test_rips_persistence_in_dimension(6), std::invalid_argument);
+}
+
 BOOST_AUTO_TEST_CASE( rips_persistent_cohomology_single_field_dim_11 )
 {
   test_rips_persistence_in_dimension(11);