adding shift method to polytope interface

src/storm/storage/geometry/Polytope.cpp

@@ -167,6 +167,16 @@ namespace storm {
                 return std::vector<Point>();
             }
 
+            template <typename ValueType>
+            std::shared_ptr<Polytope<ValueType>> Polytope<ValueType>::shift(Point const& b) const {
+                // perform an affine transformation with identity matrix
+                std::vector<Point> idMatrix(b.size(), Point(b.size(), storm::utility::zero<ValueType>()));
+                for (uint64_t i = 0; i < b.size(); ++i) {
+                    idMatrix[i][i] = storm::utility::one<ValueType>();
+                }
+                return affineTransformation(idMatrix, b);
+            }
+
             template <typename ValueType>
             std::shared_ptr<Polytope<ValueType>> Polytope<ValueType>::downwardClosure() const {
                 return createDownwardClosure(this->getVertices());

src/storm/storage/geometry/Polytope.h

@@ -116,6 +116,13 @@ namespace storm {
                  */
                 virtual std::shared_ptr<Polytope<ValueType>> affineTransformation(std::vector<Point> const& matrix, Point const& vector) const = 0;
                 
+                /*!
+                 * Returns the Polytope described by the set {x+b | x \in this}
+                 *
+                 * @param b the transformation offset
+                 */
+                std::shared_ptr<Polytope<ValueType>> shift(Point const& b) const;
+                
                 /*!
                  * Returns the downward closure of this, i.e., the set { x | ex. y \in P : x<=y} where P is this Polytope.
                  */