tree 75459f6bf82c80508e43cb88173ecf4e335d7909
parent 54fc9423673886ac9ed3fe329a80f07544aeea70
author Alex Stewart <alexs.mac@gmail.com> 1383840602 +0000
committer Sameer Agarwal <sandwichmaker@gmail.com> 1384450810 +0000

Fixes for some line search bugs & corner cases.

- Increase precision of numeric values output in error messages to
  allow for easier debugging.
- Ensure termination after Wolfe search bracketing phase if bracket
  width has been shrunk to below tolerance.
- Cleaned up return value for BracketingPhase(), now false iff
  optimisation should stop, true otherwise.
- Fix bug whereby we would mark a step size as satisfying the Wolfe
  conditions when it did not due to numerical issues in the cost
  function.
- Adding explanation of a subtlety in which a zoom could still be
  acceptably invoked with bracket_low.f > bracket_high.f.
- Replacing hard check of a pre-condition of ZoomPhase() with a
  conditional return if not satisfied to address issue whereby a
  bracket could be incorrectly identified due to inconsistent values
  & gradients returned from the cost function.
- Adding missing check for step size validity in line search minimizer.
- Adding ToDebugString() for FunctionSample.

Change-Id: Iad98e635749877f80c079ebad126bf022d82232d