Comment on ldlt

[WhiskyDelta]

/**

• Solves this * result = b, and returns result
• ldlt is fast, needs this to be positive or negative definite */

I think it should say: needs this to be positive or negative SEMIdefinite

http://eigen.tuxfamily.org/dox-devel/group__TutorialLinearAlgebra.html

Just a slight difference.

[hughperkins]

Thanks! Updated.