723 update support_max after setting a new parameter (#724)

Co-authored-by: Martin J. Kühn <[email protected]>

Author: annawendler

cpp/memilio/epidemiology/state_age_function.h

@@ -132,12 +132,18 @@ struct StateAgeFunction {
      * @brief Set the m_parameter object.
      * 
      * Can be used to set the m_parameter object, which specifies the used function.
+     * The maximum support of a function may be costly to evaluate. In order to not always reevaluate or recompute the
+     * support when the user asks for it, a cached value is used. If m_support_max is set to -1, the cached value is
+     * deleted and a recomputation is done the next time the user asks for the support. As the support (potentially)
+     * depends on the m_parameter object, the cached value has to be deleted. For details see get_support_max().
      *
      *@param[in] new_parameter New parameter for StateAgeFunction.
      */
     void set_parameter(ScalarType new_parameter)
     {
         m_parameter = new_parameter;
+
+        m_support_max = -1.;
     }
 
     /**
@@ -156,7 +162,7 @@ struct StateAgeFunction {
      */
     virtual ScalarType get_support_max(ScalarType dt, ScalarType tol = 1e-10)
     {
-        ScalarType support_max = 0;
+        ScalarType support_max = 0.;
 
         if (!floating_point_equal(m_support_tol, tol, 1e-14) || floating_point_equal(m_support_max, -1., 1e-14)) {
             while (eval(support_max) >= tol) {
@@ -288,7 +294,8 @@ struct SmootherCosine : public StateAgeFunction {
     {
         unused(dt);
         unused(tol);
-        return m_parameter;
+        m_support_max = m_parameter;
+        return m_support_max;
     }
 
 protected:
@@ -350,11 +357,12 @@ struct ConstantFunction : public StateAgeFunction {
 
         unused(dt);
         unused(tol);
+        m_support_max = -2.;
 
         log_error("This function is not suited to be a TransitionDistribution. Do not call in case of StateAgeFunctions"
                   "of type b); see documentation of StateAgeFunction Base class.");
 
-        return (ScalarType)(-2);
+        return m_support_max;
     }
 
 protected:

cpp/tests/test_ide_secir.cpp

@@ -432,7 +432,7 @@ TEST(IdeSecir, checkProportionRecoveredDeath)
         init.add_time_point(init.get_last_time() + dt, vec_init);
     }
 
-    // Initialize two models.
+    // Initialize model.
     mio::isecir::Model model(std::move(init), N, Dead_before);
 
     // Set working parameters.

cpp/tests/test_state_age_function.cpp

@@ -104,14 +104,21 @@ TEST(TestStateAgeFunction, testGetSupportMax)
     ScalarType dt = 0.5;
 
     // test get_support_max for all derived classes as this method can be overridden
+    // Check that the maximum support is correct after setting the parameter object of a StateAgeFunction.
     mio::ExponentialDecay expdecay(1.0);
     EXPECT_NEAR(expdecay.get_support_max(dt), 23.5, 1e-14);
+    expdecay.set_parameter(2.0);
+    EXPECT_NEAR(expdecay.get_support_max(dt), 12.0, 1e-14);
 
     mio::SmootherCosine smoothcos(1.0);
     EXPECT_NEAR(smoothcos.get_support_max(dt), 1.0, 1e-14);
+    smoothcos.set_parameter(2.0);
+    EXPECT_NEAR(smoothcos.get_support_max(dt), 2.0, 1e-14);
 
     mio::ConstantFunction constfunc(1.0);
     EXPECT_NEAR(constfunc.get_support_max(dt), -2.0, 1e-14);
+    constfunc.set_parameter(2.0);
+    EXPECT_NEAR(constfunc.get_support_max(dt), -2.0, 1e-14);
 }
 
 TEST(TestStateAgeFunction, testSAFWrapperSpecialMember)
@@ -150,7 +157,7 @@ TEST(TestStateAgeFunction, testSAFWrapperSpecialMember)
     // test true copy, not reference
     wrapper.set_parameter(2.0);
     EXPECT_NE(wrapper.get_parameter(), wrapper4.get_parameter());
-    wrapper.set_parameter(1.0);    
+    wrapper.set_parameter(1.0);
 
     // move assignment
     mio::StateAgeFunctionWrapper wrapper5 = std::move(wrapper4);