imaging::SteepestDescent Class Reference
[Minimization Module]

Minimizes differentiable energies using steepest descent. More...

#include <SteepestDescent.hpp>

Inheritance diagram for imaging::SteepestDescent:


List of all members.

Public Member Functions

 SteepestDescent (DifferentiableEnergyInterface &energy, float_t min_gradient_norm, float_t step_size)
bool minimize (size_t n_max_steps, size_t &n_actual_steps)

Detailed Description

Minimizes differentiable energies using steepest descent.

Minimizes a given energy $E$ which is initialized to a vector $x_0 \in \mathbf{R}^n$ by iteratively computing

\[ x_{i+1} = -\tau \nabla E(x_i)\,, \]

for a step size $\tau > 0$.

Constructor & Destructor Documentation

imaging::SteepestDescent::SteepestDescent ( DifferentiableEnergyInterface energy,
float_t  min_gradient_norm,
float_t  step_size 

Construct a SteepestDescent object to minimize energy. If the L2-norm of the gradient of the functional falls below min_gradient_norm the algorithm stops. The parameter step_size refers to the step size $\tau$. To actually start the minimization the user must call minimize().

Member Function Documentation

bool imaging::SteepestDescent::minimize ( size_t  n_max_steps,
size_t n_actual_steps 
) [virtual]

Start the minimization process. At most n_max_steps will be performed. If the convergence criterion (as set in the constructor) is met before the number of maximal steps is reached the function returns true. Otherwise it returns false. The actual number of performed stops is stored in n_steps. Upon return, the energy (as set in the constructor) will have the solution as its current argument.

Implements imaging::MinimizerInterface.

References imaging::EnergyInterface::current_argument(), imaging::EnergyInterface::current_energy(), imaging::DifferentiableEnergyInterface::current_gradient(), imaging::MessageInterface::DEBUG_ONLY, imaging::MessageInterface::out, and imaging::DifferentiableEnergyInterface::set_argument_with_gradient().

The documentation for this class was generated from the following files:

Generated on Tue Feb 10 10:01:31 2009 for imaging2 by  doxygen 1.5.5