Remove use for flipFunction in Permittivity

src/environment/Permittivity.cpp

@@ -35,8 +35,7 @@ Permittivity::Permittivity(std::shared_ptr<mrchem::Cavity> cavity, double epsilo
 
 double Permittivity::evalf(const mrcpp::Coord<3> &r) const {
     auto c_pin = this->cavity;
-    auto epsilon = this->in * std::exp(std::log(this->out / this->in) * (1 - c_pin->evalf(r)));
-    return (this->inverse) ? 1.0 / epsilon : epsilon;
+    return this->in * std::exp(std::log(this->out / this->in) * (1 - c_pin->evalf(r)));
 }
 
 void Permittivity::printHeader() const {

src/environment/Permittivity.h

@@ -65,15 +65,10 @@ class Permittivity final : public StepFunction {
      */
     double evalf(const mrcpp::Coord<3> &r) const override;
 
-    void flipFunction(bool is_inverse) { this->inverse = is_inverse; }
-    auto isInverse() const { return this->inverse; }
-
     void printHeader() const override;
 
 private:
     std::string formulation = "exponential";
-    bool inverse = false; //!< State of #evalf. When this is false, evalf returns the standard value, but when it is true,
-                          //!< evalf returns 1/epsilon.
 };
 
 } // namespace mrchem

src/environment/SCRF.cpp

@@ -119,13 +119,11 @@ mrcpp::ComplexFunction SCRF::solvePoissonEquation(const mrcpp::ComplexFunction &
     mrcpp::ComplexFunction Vr_np1;
     Vr_np1.alloc(NUMBER::Real);
 
-    this->epsilon.flipFunction(true);
-
+    auto eps_inv_func = mrcpp::AnalyticFunction<3>([this](const mrcpp::Coord<3> &r) { return 1.0 / this->epsilon.evalf(r); });
     Density rho_tot(false);
     computeDensities(Phi, rho_tot);
 
-    mrcpp::cplxfunc::multiply(first_term, rho_tot, this->epsilon, this->apply_prec);
-    this->epsilon.flipFunction(false);
+    mrcpp::cplxfunc::multiply(first_term, rho_tot, eps_inv_func, this->apply_prec);
 
     mrcpp::cplxfunc::add(rho_eff, 1.0, first_term, -1.0, rho_tot, -1.0);
     rho_tot.free(NUMBER::Real);