Merge branch 'develop-F_SQRT' into 'develop'

F_SQRT

See merge request !19

include/tadah/models/descriptors/dm/dm_func.h

@@ -8,13 +8,26 @@
 
 class F_Base {
 public:
-  virtual double calc_F(double rho, size_t c)=0;
-  virtual double calc_dF(double rho, size_t c)=0;
+  /**
+   * @brief Calculates the embedding function value.
+   * @param rho Electron density.
+   * @param p Index for model parameters.
+   * @return Function value F(rho).
+   */
+  virtual double calc_F(double rho, size_t p) = 0;
+
+  /**
+   * @brief Calculates the first derivative of the embedding function.
+   * @param rho Electron density.
+   * @param p Index for model parameters.
+   * @return Derivative dF/d(rho).
+   */
+  virtual double calc_dF(double rho, size_t p) = 0;
 };
 
 /**
  * @class F_RLR
- * @brief Implements an embedding function of the form: \f$ s x \log(c x) \f$
+ * @brief Implements an embedding function of the form: \f$ s \rho \log(c \rho) \f$
  *
  * This class supports embedding functions characterized by two main parameters:
  * - **SEMBFUNC**: Controls the depth, \f$ s \f$, of the embedding function.
@@ -32,10 +45,61 @@ private:
 public:
   F_RLR(Config &conf);
   F_RLR();
-  double calc_F(double rho,size_t c);
-  double calc_dF(double rho,size_t c);
+  double calc_F(double rho,size_t p) override;
+  double calc_dF(double rho,size_t p) override;
   //~F_RLR() {
   // Do not delete config!
   //}
 };
+
+/**
+ * @class F_SQRT
+ * @brief Implements \f$ s \sqrt(\rho) \f$.
+ *
+ * Optional parameter:
+ * - **SEMBFUNC**: Controls the strength, \f$ s \f$, of the embedding function.
+ *   If no; value is provided, the default is 1.
+ *  
+ */
+class F_SQRT : public F_Base {
+private:
+  Config *config = nullptr; ///< Configuration object (not owned by this class).
+  v_type sgrid;             ///< Controls depth or scaling factor.
+
+public:
+  /**
+   * @brief Constructs F_SQRT from a Config object.
+   * @param conf Reference to a Config instance.
+   *
+   * The constructor extracts or initializes relevant parameter for the model from
+   * the provided configuration.
+   */
+  F_SQRT(Config &conf);
+
+  /**
+   * @brief Default constructor for F_SQRT.
+   *
+   * This version does not initialize from a Config object. Users must
+   * manually set sgrid if this constructor is used.
+   */
+  F_SQRT();
+
+  /**
+   * @brief Calculates the embedding function value using a square-root dependence.
+   * @param rho Electron density.
+   * @param p Index for model parameters. Here p=0
+   * @return Embedding function value \f$ F(\rho) = s_{p} \sqrt{ c_{p} \rho } \f$.
+   */
+  double calc_F(double rho, size_t p) override;
+
+  /**
+   * @brief Calculates the derivative of the square-root embedding function.
+   * @param rho Electron density.
+   * @param p Index for model parameters. Here p=0
+   * @return First derivative \f$ dF/d\rho = \frac{s_{p} \, {2 \sqrt{\rho}} \f$.
+   */
+  double calc_dF(double rho, size_t p) override;
+};
+
+
 #endif

src/dm_func.cpp

@@ -12,15 +12,45 @@ F_RLR::F_RLR(Config &conf):
 }
 F_RLR::F_RLR():
   config(nullptr)
+{}
+double F_RLR::calc_F(double rho,size_t p) {
+  if (rho>0)
+    return sgrid[p]*rho*log(cgrid[p]*rho);
+  return 0;
+}
+double F_RLR::calc_dF(double rho,size_t p) {
+  if (rho>0)
+    return sgrid[p]*(log(cgrid[p]*rho)+1);
+  return sgrid[p];
+}
+
+//////////////////////////
+// F_SQRT
+F_SQRT::F_SQRT(Config &conf):
+  config(&conf)
 {
+  if (!config->get<bool>("INITMB"))
+    return;
+  if (config->exist("SEMBFUNC")) {
+    D_Base::get_grid(*config, "SEMBFUNC", sgrid);
+  } else {
+    sgrid.resize(1);
+    sgrid[0] = 1.0;
+  }
 }
-double F_RLR::calc_F(double rho,size_t c) {
+F_SQRT::F_SQRT():
+  config(nullptr)
+{
+  sgrid.resize(1);
+  sgrid[0] = 1.0;
+}
+double F_SQRT::calc_F(double rho,size_t p) {
   if (rho>0)
-    return sgrid[c]*rho*log(cgrid[c]*rho);
+    return sgrid[p]*std::sqrt(rho);
   return 0;
 }
-double F_RLR::calc_dF(double rho,size_t c) {
+double F_SQRT::calc_dF(double rho,size_t p) {
   if (rho>0)
-    return sgrid[c]*(log(cgrid[c]*rho)+1);
-  return sgrid[c];
+    return 0.5*sgrid[p]/(std::sqrt(rho));
+  return 0;
 }

tests/test_dm_func.cpp

+#include "catch2/catch.hpp"
+#include <tadah/models/descriptors/dm/dm_func.h>
+
+#include <cmath>
+#include <cassert>
+
+/**
+ * @test Checks F_RLR behavior with a simple configuration.
+ * Ensures no NaN is returned and verifies plausibility of results.
+ */
+TEST_CASE("F_RLR: Basic Function and Derivative", "[F_RLR]")
+{
+  // Reason: "INITMB=true" triggers parameter grid load in F_RLR constructor
+  Config c;
+  c.remove("INITMB");
+  c.add("INITMB", "true");
+  c.add("SEMBFUNC", 0.2);
+  c.add("CEMBFUNC", 0.3);
+
+  F_RLR rlr(c);
+
+  double rho = 2.0;
+  size_t p = 0; // Single parameter index
+  double valF = rlr.calc_F(rho, p);
+  double valdF = rlr.calc_dF(rho, p);
+
+  // Reason: Checking for no NaN or inf
+  REQUIRE_FALSE(std::isnan(valF));
+  REQUIRE_FALSE(std::isinf(valF));
+  REQUIRE_FALSE(std::isnan(valdF));
+  REQUIRE_FALSE(std::isinf(valdF));
+
+  // Basic range checks for sanity (not strict correctness)
+  REQUIRE(valF != 0.0);
+  REQUIRE(valdF != 0.0);
+}
+
+/**
+ * @test Checks F_SQRT behavior with a simple configuration.
+ * Ensures no NaN is returned and verifies plausibility of results.
+ */
+TEST_CASE("F_SQRT: Basic Function and Derivative", "[F_SQRT]")
+{
+  // Reason: "INITMB=true" triggers sgrid load in F_SQRT constructor
+  Config c;
+  c.remove("INITMB");
+  c.add("INITMB", "true");
+  c.add("SEMBFUNC", 0.2);
+
+  F_SQRT sqrt_func(c);
+
+  double rho = 4.0;
+  size_t p = 0; // Single parameter index
+  double valF = sqrt_func.calc_F(rho, p);
+  double valdF = sqrt_func.calc_dF(rho, p);
+
+  // Reason: Checking for no NaN or inf
+  REQUIRE_FALSE(std::isnan(valF));
+  REQUIRE_FALSE(std::isinf(valF));
+  REQUIRE_FALSE(std::isnan(valdF));
+  REQUIRE_FALSE(std::isinf(valdF));
+
+  // Basic numeric checks
+  // s = 0.2, sqrt(4.0) = 2.0, so expected = 0.4 (ideal, ignoring round-off)
+  REQUIRE(valF == Approx(0.4).margin(1e-12));
+
+  // Derivative: 0.5*s / sqrt(rho) => 0.5*0.2/2.0 = 0.05
+  REQUIRE(valdF == Approx(0.05).margin(1e-12));
+}