stan-dev/stan — pull request #346 by mbrubake (2013-10-30 00:21:56+00:00)
Title: Unit test LDLT_factor better and fix derivative bug

This pull request:
* Adds unit tests for LDLT_factor (resolving issue #45). The _ldlt variants of mdivide, log_determinant, trace_inv_quad_form and trace_gen_inv_quad_form are all now directly tested.
* Fixes the gradient bug in trace_inv_quad_form_ldlt
* Reenables the use of trace_inv_quad_form_ldlt in multi_normal
* Uses trace_inv_quad_form_ldlt in multi_student_t_log
* Adds gradient testing on multi_student_t_log