migrated Helix

corsika/detail/framework/geometry/Helix.inl

@@ -17,23 +17,24 @@
 
 namespace corsika {
 
-  Point Helix::GetPosition(TimeType t) const {
-    return r0 + vPar * t +
-           (vPerp * (cos(omegaC * t) - 1) + uPerp * sin(omegaC * t)) / omegaC;
-  }
+  LengthType Helix::getRadius() const { return radius_; }
 
-  Point Helix::PositionFromArclength(LengthType l) const {
-    return GetPosition(TimeFromArclength(l));
+  Point Helix::getPosition(TimeType t) const {
+    return r0_ + vPar_ * t +
+           (vPerp_ * (std::cos(omegaC_ * t) - 1) + uPerp_ * std::sin(omegaC_ * t)) /
+               omegaC_;
   }
 
-  LengthType Helix::GetRadius() const { return radius; }
+  Point Helix::getPositionFromArclength(LengthType l) const {
+    return getPosition(getTimeFromArclength(l));
+  }
 
-  LengthType Helix::ArcLength(TimeType t1, TimeType t2) const {
-    return (vPar + vPerp).norm() * (t2 - t1);
+  LengthType Helix::getArcLength(TimeType t1, TimeType t2) const {
+    return (vPar_ + vPerp_).norm() * (t2 - t1);
   }
 
-  TimeType Helix::TimeFromArclength(LengthType l) const {
-    return l / (vPar + vPerp).norm();
+  TimeType Helix::getTimeFromArclength(LengthType l) const {
+    return l / (vPar_ + vPerp_).norm();
   }
 
 } // namespace corsika

corsika/framework/geometry/Helix.hpp

@@ -14,8 +14,9 @@ n/*
 #include <corsika/framework/geometry/Vector.hpp>
 
 namespace corsika {
+
   /*!
-   * \class Helix
+   * Defines a helical path
    *
    * A Helix is defined by the cyclotron frequency \f$ \omega_c \f$, the initial
    * Point r0 and
@@ -30,34 +31,36 @@ namespace corsika {
 
   class Helix {
 
-    using VelocityVec = Vector<SpeedType::dimension_type> ;
-
-    Point const r0;
-    FrequencyType const omegaC;
-    VelocityVec const vPar;
-    VelocityVec const vPerp, uPerp;
-
-    LengthType const radius;
+    ///! \todo move VelocityVec into PhysicalUnits
+    using VelocityVec = Vector<SpeedType::dimension_type>;
 
   public:
     Helix(Point const& pR0, FrequencyType pOmegaC, VelocityVec const& pvPar,
           VelocityVec const& pvPerp)
-        : r0(pR0)
-        , omegaC(pOmegaC)
-        , vPar(pvPar)
-        , vPerp(pvPerp)
-        , uPerp(vPerp.cross(vPar.normalized()))
-        , radius(pvPar.norm() / abs(pOmegaC)) {}
+        : r0_(pR0)
+        , omegaC_(pOmegaC)
+        , vPar_(pvPar)
+        , vPerp_(pvPerp)
+        , uPerp_(vPerp_.cross(vPar_.normalized()))
+        , radius_(pvPar.norm() / abs(pOmegaC)) {}
 
-    inline Point GetPosition(TimeType t) const;
+    inline LengthType getRadius() const;
 
-    inline Point PositionFromArclength(LengthType l) const;
+    inline Point getPosition(TimeType t) const;
+    
+    inline Point getPositionFromArclength(LengthType l) const;
 
-    inline LengthType GetRadius() const;
+    inline LengthType getArcLength(TimeType t1, TimeType t2) const;
 
-    inline LengthType ArcLength(TimeType t1, TimeType t2) const;
+    inline TimeType getTimeFromArclength(LengthType l) const;
 
-    inline TimeType TimeFromArclength(LengthType l) const;
+  private:
+    Point r0_;             ///! origin of helix, but this is in the center of the
+                           ///! "cylinder" on which the helix rotates
+    FrequencyType omegaC_; ///! speed of angular rotation
+    VelocityVec vPar_;     ///! speed along direction of "cylinder"
+    VelocityVec vPerp_, uPerp_; 
+    LengthType radius_;
   };
 
 } // namespace corsika

tests/framework/CMakeLists.txt

@@ -6,6 +6,7 @@ set (test_framework_sources
   #testCOMBoost.cpp #FIXME: reenable this
   #testCorsikaFenv.cpp # does not work because of use of exceptions in catch2
   testFourVector.cpp
+  testHelix.cpp
   testFunctionTimer.cpp
   testGeometry.cpp
   testLogging.cpp

tests/framework/testGeometry.cpp

@@ -11,7 +11,6 @@
 #include <cmath>
 #include <corsika/framework/core/PhysicalUnits.hpp>
 #include <corsika/framework/geometry/CoordinateSystem.hpp>
-#include <corsika/framework/geometry/Helix.hpp>
 #include <corsika/framework/geometry/Line.hpp>
 #include <corsika/framework/geometry/Point.hpp>
 #include <corsika/framework/geometry/RootCoordinateSystem.hpp>
@@ -19,7 +18,6 @@
 #include <corsika/framework/geometry/Trajectory.hpp>
 
 using namespace corsika;
-using namespace corsika::units::si;
 
 double constexpr absMargin = 1.0e-8;
 
@@ -233,31 +231,4 @@ TEST_CASE("Trajectories") {
               .eVector.norm() == Approx(0).margin(absMargin));
   }
 
-  SECTION("Helix") {
-    Vector<SpeedType::dimension_type> const vPar(
-        rootCS, {0_m / second, 0_m / second, 4_m / second});
-
-    Vector<SpeedType::dimension_type> const vPerp(
-        rootCS, {3_m / second, 0_m / second, 0_m / second});
-
-    auto const T = 1_s;
-    auto const omegaC = 2 * M_PI / T;
-
-    Helix const helix(r0, omegaC, vPar, vPerp);
-
-    CHECK((helix.GetPosition(1_s).GetCoordinates() -
-           QuantityVector<length_d>(0_m, 0_m, 4_m))
-              .norm()
-              .magnitude() == Approx(0).margin(absMargin));
-
-    CHECK((helix.GetPosition(0.25_s).GetCoordinates() -
-           QuantityVector<length_d>(-3_m / (2 * M_PI), -3_m / (2 * M_PI), 1_m))
-              .norm()
-              .magnitude() == Approx(0).margin(absMargin));
-
-    CHECK(
-        (helix.GetPosition(7_s) - helix.PositionFromArclength(helix.ArcLength(0_s, 7_s)))
-            .norm()
-            .magnitude() == Approx(0).margin(absMargin));
-  }
 }

tests/framework/testHelix.cpp

+/*
+ * (c) Copyright 2020 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#include <catch2/catch.hpp>
+
+#include <corsika/framework/geometry/Helix.hpp>
+#include <corsika/framework/core/PhysicalUnits.hpp>
+#include <corsika/framework/geometry/CoordinateSystem.hpp>
+#include <corsika/framework/geometry/Line.hpp>
+#include <corsika/framework/geometry/Point.hpp>
+#include <corsika/framework/geometry/RootCoordinateSystem.hpp>
+
+using namespace corsika;
+
+double constexpr absMargin = 1.0e-8;
+
+TEST_CASE("Helix class") {
+
+  CoordinateSystem& rootCS =
+    RootCoordinateSystem::getInstance().GetRootCoordinateSystem();
+  Point r0(rootCS, {0_m, 0_m, 0_m});
+
+  SECTION("Helix") {
+    Vector<SpeedType::dimension_type> const vPar(
+        rootCS, {0_m / second, 0_m / second, 4_m / second});
+
+    Vector<SpeedType::dimension_type> const vPerp(
+        rootCS, {3_m / second, 0_m / second, 0_m / second});
+
+    auto const T = 1_s;
+    auto const omegaC = 2 * M_PI / T;
+
+    Helix const helix(r0, omegaC, vPar, vPerp);
+
+    CHECK((helix.getPosition(1_s).GetCoordinates() -
+           QuantityVector<length_d>(0_m, 0_m, 4_m))
+              .norm()
+              .magnitude() == Approx(0).margin(absMargin));
+
+    CHECK((helix.getPosition(0.25_s).GetCoordinates() -
+           QuantityVector<length_d>(-3_m / (2 * M_PI), -3_m / (2 * M_PI), 1_m))
+              .norm()
+              .magnitude() == Approx(0).margin(absMargin));
+
+    CHECK(
+        (helix.getPosition(7_s) - helix.getPositionFromArclength(helix.getArcLength(0_s, 7_s)))
+            .norm()
+            .magnitude() == Approx(0).margin(absMargin));
+
+    /*
+    // we have to consider this, if we need it
+    auto const t = 1234_s;
+    Trajectory<Helix> const base(helix, t);
+    CHECK(helix.getPosition(t).GetCoordinates() == base.GetPosition(1.).GetCoordinates());
+
+    CHECK(base.ArcLength(0_s, 1_s) / 1_m == Approx(5));
+    */
+  }
+
+}
+