tree 7d12e48bfd38d4a4b4449c7e952ff35f1bcdd422
parent dcee120bac04911bf01d8365bddca87c74ce2af9
author Sameer Agarwal <sameeragarwal@google.com> 1387400818 -0800
committer Sameer Agarwal <sameeragarwal@google.com> 1387401012 -0800

Handle empty problems consistently.

Until now Ceres was inconsistent in the way it handled a solve
call on an "empty" Problem. If the problem did not contain
any residual or parameter blocks, it failed. However, if after
constructing the reduced program, the problem was found to not
contain any modifiable parameter blocks, it was considered a valid
problem which had a constant objective function value.

When creating problems automatically, it is often the case that
an empty problem is a corner case. This change makes handling this
corner case consistent with the rest of Ceres logic.

Change-Id: Ia9da09fbf5d5cd7eae6b39a92c1976b8645db9fe