Refs #10305. Draft of symbol determination algorithm for rotations.

mantidproject · Feb 6, 2015 · f3d2cfc · f3d2cfc
1 parent 2f4d3a6
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Showing 3 changed files with 90 additions and 17 deletions.
diff --git a/Code/Mantid/Framework/Geometry/inc/MantidGeometry/Crystal/SymmetryElement.h b/Code/Mantid/Framework/Geometry/inc/MantidGeometry/Crystal/SymmetryElement.h
@@ -119,6 +119,9 @@ class MANTID_GEOMETRY_DLL SymmetryElementRotation
   RotationSense determineRotationSense(const SymmetryOperation &operation,
                                        const V3R &rotationAxis) const;
 
+  bool isNotRotation(int determinant, int trace) const;
+  std::string determineSymbol(const SymmetryOperation &operation) const;
+
   RotationSense m_rotationSense;
 };
 

diff --git a/Code/Mantid/Framework/Geometry/src/Crystal/SymmetryElement.cpp b/Code/Mantid/Framework/Geometry/src/Crystal/SymmetryElement.cpp
@@ -3,6 +3,7 @@
 
 #include <gsl/gsl_eigen.h>
 #include <gsl/gsl_complex_math.h>
+#include <boost/lexical_cast.hpp>
 
 namespace Mantid {
 namespace Geometry {
@@ -149,7 +150,14 @@ SymmetryElementRotation::SymmetryElementRotation()
     : SymmetryElementWithAxis() {}
 
 void SymmetryElementRotation::init(const SymmetryOperation &operation) {
-  UNUSED_ARG(operation);
+  int determinant = operation.matrix().determinant();
+  int trace = operation.matrix().Trace();
+
+  if (isNotRotation(determinant, trace)) {
+    throw std::invalid_argument(
+        "SymmetryOperation " + operation.identifier() +
+        " cannot be used to construct SymmetryElementRotation.");
+  }
 }
 
 SymmetryElementRotation::RotationSense
@@ -168,11 +176,56 @@ SymmetryElementRotation::determineRotationSense(
 
   double determinant = matrix.determinant() * operation.matrix().determinant();
 
-  if(determinant < 0) {
-      return Negative;
+  if (determinant < 0) {
+    return Negative;
   } else {
-      return Positive;
+    return Positive;
+  }
+}
+
+bool SymmetryElementRotation::isNotRotation(int determinant, int trace) const {
+  // It's an inversion or identity
+  if (abs(trace) == 3) {
+    return true;
+  }
+
+  // It's a mirror
+  if (trace == 1 && determinant == -1) {
+    return true;
+  }
+
+  return false;
+}
+
+std::string SymmetryElementRotation::determineSymbol(
+    const SymmetryOperation &operation) const {
+
+  const Kernel::IntMatrix &matrix = operation.matrix();
+
+  int trace = matrix.Trace();
+  int determinant = matrix.determinant();
+
+  if (trace == 0 && determinant == -1) {
+    return "-3";
   }
+
+  std::string symbol;
+
+  if (determinant < 0) {
+    symbol += "-";
+  }
+
+  symbol += boost::lexical_cast<std::string>(operation.order());
+
+  int translation =
+      static_cast<int>(static_cast<double>(operation.order()) *
+                       Kernel::V3D(determineTranslation(operation)).norm());
+
+  if (translation != 0) {
+    symbol += boost::lexical_cast<std::string>(translation);
+  }
+
+  return symbol;
 }
 
 SymmetryElementMirror::SymmetryElementMirror() : SymmetryElementWithAxis() {}

diff --git a/Code/Mantid/Framework/Geometry/test/SymmetryElementTest.h b/Code/Mantid/Framework/Geometry/test/SymmetryElementTest.h
@@ -7,6 +7,7 @@
 
 #include "MantidGeometry/Crystal/SymmetryElement.h"
 #include "MantidGeometry/Crystal/SpaceGroupFactory.h"
+#include "MantidGeometry/Crystal/PointGroupFactory.h"
 
 using namespace Mantid::Geometry;
 using namespace Mantid::Kernel;
@@ -206,33 +207,49 @@ class SymmetryElementTest : public CxxTest::TestSuite {
 
     // Test case 2: 6 [0 0 1] (Positive/Negative) in hexagonal system
     SymmetryOperation sixFoldRotationZPlus("x-y,x,z");
-    V3R rotationAxisZ =
-        element.determineAxis(sixFoldRotationZPlus.matrix());
-    TS_ASSERT_EQUALS(element.determineRotationSense(
-                         sixFoldRotationZPlus, rotationAxisZ),
-                     SymmetryElementRotation::Positive);
+    V3R rotationAxisZ = element.determineAxis(sixFoldRotationZPlus.matrix());
+    TS_ASSERT_EQUALS(
+        element.determineRotationSense(sixFoldRotationZPlus, rotationAxisZ),
+        SymmetryElementRotation::Positive);
 
     SymmetryOperation sixFoldRotationZMinus("y,y-x,z");
-    V3R rotationAxisZ2 =
-        element.determineAxis(sixFoldRotationZMinus.matrix());
+    V3R rotationAxisZ2 = element.determineAxis(sixFoldRotationZMinus.matrix());
 
     TS_ASSERT_EQUALS(rotationAxisZ, rotationAxisZ2);
 
-    TS_ASSERT_EQUALS(element.determineRotationSense(
-                         sixFoldRotationZMinus, rotationAxisZ2),
-                     SymmetryElementRotation::Negative);
+    TS_ASSERT_EQUALS(
+        element.determineRotationSense(sixFoldRotationZMinus, rotationAxisZ2),
+        SymmetryElementRotation::Negative);
   }
 
-  void xtestSymmetryElementWithAxisSpaceGroup() {
-    MockSymmetryElementWithAxis element;
+  void testSymmetryElementRotationDetermineSymbol() {
+    TestableSymmetryElementRotation element;
+
+    SymmetryOperation sixFoldRotationZMinus("y,y-x,z");
+
+    std::cout << element.determineSymbol(sixFoldRotationZMinus) << std::endl;
+  }
+
+  void testSymmetryElementWithAxisSpaceGroup() {
+    TestableSymmetryElementRotation element;
 
     SpaceGroup_const_sptr sg =
         SpaceGroupFactory::Instance().createSpaceGroup("P m -3");
 
+    PointGroup_sptr pg =
+        PointGroupFactory::Instance().createPointGroupFromSpaceGroupSymbol(
+            sg->hmSymbol());
+
     std::vector<SymmetryOperation> ops = sg->getSymmetryOperations();
     for (auto it = ops.begin(); it != ops.end(); ++it) {
+      V3R axis = element.determineAxis((*it).matrix());
+      SymmetryElementRotation::RotationSense sense =
+          element.determineRotationSense(*it, axis);
       std::cout << (*it).identifier() << ": " << (*it).order() << " "
-                << element.determineAxis((*it).matrix()) << std::endl;
+                << pg->getReflectionFamily(axis) << " "
+                << element.determineSymbol(*it)
+                << (sense == SymmetryElementRotation::Positive ? "+" : "-")
+                << std::endl;
     }
   }