Fixed LineEnergy. Optimized the use of Energy class in LineSearchStrongWolfe.

demos/wiener_filter_hamiltonian.py

@@ -78,17 +78,17 @@ if __name__ == "__main__":
     D = PropagatorOperator(S=S, N=N, R=R)
 
     def distance_measure(energy, iteration):
-        pass
-        #print (iteration, ((x-ss).norm()/ss.norm()).real)
+        x = energy.position
+        print (iteration, ((x-ss).norm()/ss.norm()).real)
 
     minimizer = SteepestDescent(convergence_tolerance=0,
                                 iteration_limit=50,
                                 callback=distance_measure)
 
-#    minimizer = VL_BFGS(convergence_tolerance=0,
-#                        iteration_limit=50,
-#                        callback=distance_measure,
-#                        max_history_length=5)
+    minimizer = VL_BFGS(convergence_tolerance=0,
+                        iteration_limit=50,
+                        callback=distance_measure,
+                        max_history_length=5)
 
     m0 = Field(s_space, val=1)
 

nifty/energies/line_energy.py

@@ -4,19 +4,22 @@ from .energy import Energy
 
 
 class LineEnergy(Energy):
-    def __init__(self, position, energy, line_direction):
-        self.energy = energy
-        self.line_direction = line_direction
+    def __init__(self, position, energy, line_direction, zero_point=None):
         super(LineEnergy, self).__init__(position=position)
+        self.line_direction = line_direction
+
+        if zero_point is None:
+            zero_point = energy.position
+        self._zero_point = zero_point
+
+        position_on_line = self._zero_point + self.position*line_direction
+        self.energy = energy.at(position=position_on_line)
 
     def at(self, position):
-        if position == 0:
-            return self
-        else:
-            full_position = self.position + self.line_direction*position
-            return self.__class__(full_position,
+        return self.__class__(position,
                               self.energy,
-                                  self.line_direction)
+                              self.line_direction,
+                              zero_point=self._zero_point)
 
     @property
     def value(self):

nifty/minimization/line_searching/line_search.py

@@ -59,6 +59,5 @@ class LineSearch(object, Loggable):
         self.f_k_minus_1 = f_k_minus_1
 
     @abc.abstractmethod
-    def perform_line_search(self, xk, pk, f_k=None, fprime_k=None,
-                            f_k_minus_1=None):
+    def perform_line_search(self, energy, pk, f_k_minus_1=None):
         raise NotImplementedError

nifty/minimization/line_searching/line_search_strong_wolfe.py

@@ -54,8 +54,9 @@ class LineSearchStrongWolfe(LineSearch):
 
         # initialize the zero phis
         old_phi_0 = self.f_k_minus_1
-        phi_0 = self.line_energy.at(0).value
-        phiprime_0 = self.line_energy.at(0).gradient
+        energy_0 = self.line_energy.at(0)
+        phi_0 = energy_0.value
+        phiprime_0 = energy_0.gradient
 
         if phiprime_0 == 0:
             self.logger.warn("Flat gradient in search direction.")
@@ -82,11 +83,13 @@ class LineSearchStrongWolfe(LineSearch):
                 self.logger.warn("Increment size became 0.")
                 alpha_star = 0.
                 phi_star = phi_0
+                energy_star = energy_0
                 break
 
             if (phi_alpha1 > phi_0 + c1*alpha1*phiprime_0) or \
                ((phi_alpha1 >= phi_alpha0) and (i > 1)):
-                (alpha_star, phi_star) = self._zoom(alpha0, alpha1,
+                (alpha_star, phi_star, energy_star) = self._zoom(
+                                                    alpha0, alpha1,
                                                     phi_0, phiprime_0,
                                                     phi_alpha0,
                                                     phiprime_alpha0,
@@ -98,10 +101,12 @@ class LineSearchStrongWolfe(LineSearch):
             if abs(phiprime_alpha1) <= -c2*phiprime_0:
                 alpha_star = alpha1
                 phi_star = phi_alpha1
+                energy_star = energy_alpha1
                 break
 
             if phiprime_alpha1 >= 0:
-                (alpha_star, phi_star) = self._zoom(alpha1, alpha0,
+                (alpha_star, phi_star, energy_star) = self._zoom(
+                                                    alpha1, alpha0,
                                                     phi_0, phiprime_0,
                                                     phi_alpha1,
                                                     phiprime_alpha1,
@@ -119,10 +124,15 @@ class LineSearchStrongWolfe(LineSearch):
             # max_iterations was reached
             alpha_star = alpha1
             phi_star = phi_alpha1
+            energy_star = energy_alpha1
             self.logger.error("The line search algorithm did not converge.")
 
         self._last_alpha_star = alpha_star
-        return alpha_star, phi_star
+
+        # extract the full energy from the line_energy
+        energy_star = energy_star.energy
+
+        return alpha_star, phi_star, energy_star
 
     def _zoom(self, alpha_lo, alpha_hi, phi_0, phiprime_0,
               phi_lo, phiprime_lo, phi_hi, c1, c2):
@@ -176,6 +186,7 @@ class LineSearchStrongWolfe(LineSearch):
                 if abs(phiprime_alphaj) <= -c2*phiprime_0:
                     alpha_star = alpha_j
                     phi_star = phi_alphaj
+                    energy_star = energy_alphaj
                     break
                 # If not, check the sign of the slope
                 if phiprime_alphaj*delta_alpha >= 0:
@@ -188,11 +199,12 @@ class LineSearchStrongWolfe(LineSearch):
                                                    phiprime_alphaj)
 
         else:
-            alpha_star, phi_star = alpha_j, phi_alphaj
+            alpha_star, phi_star, energy_star = \
+                alpha_j, phi_alphaj, energy_alphaj
             self.logger.error("The line search algorithm (zoom) did not "
                               "converge.")
 
-        return alpha_star, phi_star
+        return alpha_star, phi_star, energy_star
 
     def _cubicmin(self, a, fa, fpa, b, fb, c, fc):
         """

nifty/minimization/quasi_newton_minimizer.py

@@ -86,13 +86,11 @@ class QuasiNewtonMinimizer(object, Loggable):
 
             # compute the step length, which minimizes energy.value along the
             # search direction
-            step_length, step_length = self.line_searcher.perform_line_search(
+            step_length, f_k, new_energy = \
+                self.line_searcher.perform_line_search(
                                                energy=energy,
                                                pk=descend_direction,
                                                f_k_minus_1=f_k_minus_1)
-            new_position = current_position + step_length * descend_direction
-            new_energy = energy.at(new_position)
-
             f_k_minus_1 = energy.value
             energy = new_energy
 

nifty/minimization/vl_bfgs.py

@@ -20,9 +20,9 @@ class VL_BFGS(QuasiNewtonMinimizer):
 
         self.max_history_length = max_history_length
 
-    def __call__(self, x0, f, fprime, f_args=()):
+    def __call__(self, energy):
         self._information_store = None
-        return super(VL_BFGS, self).__call__(x0, f, fprime, f_args=())
+        return super(VL_BFGS, self).__call__(energy)
 
     def _get_descend_direction(self, x, gradient):
         # initialize the information store if it doesn't already exist