tree f8ea66339168bbbef82a3694edfb4e99ec699ac6
parent 7b4ec98ea9cd32be826365f37621f9232d95c15b
author Sameer Agarwal <sameeragarwal@google.com> 1484524016 -0800
committer Sameer Agarwal <sameeragarwal@google.com> 1484589636 -0800

Ensure that partial evaluation of residuals triggers an error

ResidualBlock evaluation has logic to ensure that CostFunction
should always fill out the residual and jacobian arrays completely
by using a special value to pre-populate these arrays.

This works for CostFunctions with analytical Jacobians but not for
AutoDiffCostFunction and NumericDiffCostFunction Jacobians.

There is no way to fix this for NumericDiffCostFunctions without
introducing significant performance penalties but the residual
evaluation fails, which should be enough to catch such errors.

For AutoDiffCostFunction the way the Jets are default initialized
was sidestepping this check. So now, the Jet that is used to
capture the output residuals is now initialized with
kImpossibleValue, which will ensure that if the user forgets
to fill all output fields, it triggers an evaluation error.

This change required that ceres::internal::kImpossibleValue be moved
out of array_utils.h/cc to types.h.

Change-Id: I35bb0946cf0785a5d43c7b5459a2272848fb2a9b