tree 87b93832afc3f0e1a27baf549d9837e8783b0c78
parent 41675682dc9df836bf15845064cfe1087619c79d
author Sameer Agarwal <sameeragarwal@google.com> 1585861076 -0700
committer Sameer Agarwal <sameeragarwal@google.com> 1585861940 -0700

Use Ridders' method in GradientChecker.

Using Ridders' method gives orders of magnitude more accuracy compared
to central differences. This will make things slower, but this is
primarily a testing/debugging feature and the speed hit is not a
concern. This should also reduce the false positive rates when users
enable check_gradients. This is reflected the increased sensitivity of
the tests for GradientChecker.

https://github.com/ceres-solver/ceres-solver/issues/554

Change-Id: I6b871c72df55be1c31175ba062cf3c1e94e4b662