[CppAD] LuSolve

[Mitch Watrous]

Hi.

When the factors created by LuSolve contain NaN's, it should return the 
signdet equal to 0.

But in fact it sometimes generates the following assert:

		CPPAD_ASSERT_KNOWN(
			(imax < n) & (jmax < n) ,
			"AbsGeq must return true when second argument is zero"


Thanks,
Mitch