Prime meridian equivalence: increase tolerance

2 files changed, 8 insertions, 3 deletions

diff --git a/src/common.cpp b/src/common.cpp
index 2a9d17c7..bd690924 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -370,15 +370,17 @@ bool Measure::operator==(const Measure &other) PROJ_CONST_DEFN {
 /** \brief Returns whether an object is equivalent to another one.
  * @param other other object to compare to
  * @param criterion comparaison criterion.
+ * @param maxRelativeError Maximum relative error allowed.
  * @return true if objects are equivalent.
  */
 bool Measure::_isEquivalentTo(const Measure &other,
-                              util::IComparable::Criterion criterion) const {
+                              util::IComparable::Criterion criterion,
+                              double maxRelativeError) const {
     if (criterion == util::IComparable::Criterion::STRICT) {
         return operator==(other);
     }
     return std::fabs(getSIValue() - other.getSIValue()) <=
-           1e-10 * std::fabs(getSIValue());
+           maxRelativeError * std::fabs(getSIValue());
 }
 
 // ---------------------------------------------------------------------------
diff --git a/src/datum.cpp b/src/datum.cpp
index 9f9fb4ec..975a870a 100644
--- a/src/datum.cpp
+++ b/src/datum.cpp
@@ -388,7 +388,10 @@ bool PrimeMeridian::_isEquivalentTo(
         !IdentifiedObject::_isEquivalentTo(other, criterion)) {
         return false;
     }
-    return longitude()._isEquivalentTo(otherPM->longitude(), criterion);
+    // In MapInfo, the Paris prime meridian is returned as 2.3372291666667
+    // instead of the official value of 2.33722917, which is a relative
+    // error in the 1e-9 range.
+    return longitude()._isEquivalentTo(otherPM->longitude(), criterion, 1e-8);
 }
 //! @endcond