Re #21749: Use maximum precision when converting to string.

Framework/Geometry/inc/MantidGeometry/Instrument/Parameter.h

@@ -10,6 +10,7 @@
 #include <typeinfo>
 #include <vector>
 #include <stdexcept>
+#include <iomanip>
 
 namespace Mantid {
 
@@ -185,6 +186,7 @@ template <class T> void Parameter::set(const T &t) {
  */
 template <class Type> std::string ParameterType<Type>::asString() const {
   std::ostringstream str;
+  str << std::setprecision(std::numeric_limits<Type>::digits10);
   str << m_value;
   return str.str();
 }