Added optimization algorithm selection suffix in Reconstructor and Optimizer

Signed-off-by: Dmitry I. Lyakh <quant4me@gmail.com>

src/exatn/optimizer.cpp

 /** ExaTN:: Variational optimizer of a closed symmetric tensor network expansion functional
-REVISION: 2021/10/01
+REVISION: 2021/10/02
 
 Copyright (C) 2018-2021 Dmitry I. Lyakh (Liakh)
 Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
@@ -72,6 +72,12 @@ bool TensorNetworkOptimizer::optimize()
 
 
 bool TensorNetworkOptimizer::optimize(const ProcessGroup & process_group)
+{
+ return optimize_sd(process_group);
+}
+
+
+bool TensorNetworkOptimizer::optimize_sd(const ProcessGroup & process_group)
 {
  constexpr bool NORMALIZE_WITH_METRICS = true;  //whether to normalize tensor network factors with metrics or not
  constexpr double MIN_ACCEPTABLE_DENOM = 1e-13; //minimally acceptable denominator in optimal step size determination

src/exatn/optimizer.hpp

 /** ExaTN:: Variational optimizer of a closed symmetric tensor network expansion functional
-REVISION: 2021/09/08
+REVISION: 2021/10/02
 
 Copyright (C) 2018-2021 Dmitry I. Lyakh (Liakh)
 Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
@@ -67,6 +67,11 @@ public:
 
  static void resetDebugLevel(unsigned int level = 0);
 
+protected:
+
+ //Implementation based on the steepest descent algorithm:
+ bool optimize_sd(const ProcessGroup & process_group); //in: executing process group
+
 private:
 
  struct Environment{

src/exatn/reconstructor.cpp

 /** ExaTN:: Reconstructs an approximate tensor network expansion for a given tensor network expansion
-REVISION: 2021/09/14
+REVISION: 2021/10/02
 
 Copyright (C) 2018-2021 Dmitry I. Lyakh (Liakh)
 Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
@@ -111,6 +111,17 @@ bool TensorNetworkReconstructor::reconstruct(const ProcessGroup & process_group,
                                              bool rnd_init,
                                              bool nesterov,
                                              double acceptable_fidelity)
+{
+ return reconstruct_sd(process_group, residual_norm, fidelity, rnd_init, nesterov, acceptable_fidelity);
+}
+
+
+bool TensorNetworkReconstructor::reconstruct_sd(const ProcessGroup & process_group,
+                                                double * residual_norm,
+                                                double * fidelity,
+                                                bool rnd_init,
+                                                bool nesterov,
+                                                double acceptable_fidelity)
 {
  unsigned int local_rank; //local process rank within the process group
  if(!process_group.rankIsIn(exatn::getProcessRank(),&local_rank)) return true; //process is not in the group: Do nothing

src/exatn/reconstructor.hpp

 /** ExaTN:: Reconstructs an approximate tensor network expansion for a given tensor network expansion
-REVISION: 2021/09/14
+REVISION: 2021/10/02
 
 Copyright (C) 2018-2021 Dmitry I. Lyakh (Liakh)
 Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
@@ -81,6 +81,16 @@ public:
 
  static void resetDebugLevel(unsigned int level = 0);
 
+protected:
+
+ //Implementation based on the steepest descent algorithm:
+ bool reconstruct_sd(const ProcessGroup & process_group, //in: executing process group
+                     double * residual_norm,             //out: 2-norm of the residual tensor (error)
+                     double * fidelity,                  //out: squared normalized overlap (fidelity)
+                     bool rnd_init,                      //in: random initialization flag
+                     bool nesterov,                      //in: Nesterov acceleration
+                     double acceptable_fidelity);        //in: acceptable fidelity
+
 private:
 
  void reinitializeApproximant(const ProcessGroup & process_group);