Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

This is a proof from Wikipedia of Moore-Penrose inverse being the optimal solution of a least squares problem, in which there is a acronym $c.c.$ occurred in some of the equations. Mind if I ask what does that represent?

share|improve this question
    
Complex Conjugate –  Pragabhava Oct 3 '12 at 6:17
add comment

1 Answer

It means complex conjugate (of the term preceeding it), but in my opinion it is very lazy notation, for example, line 1 reads \begin{align*} \|Ax-b\|^2 & = \|Az - b + Ax - Az\|^2\\ &= \|Az - b\|^2 + (Az - b)^*(Ax - Az) + \overline{(Az - b)^*(Ax - Az)} + \|A(x - z)\|^2 \end{align*}

share|improve this answer
    
It might be lazy in this case, but if you are doing some nasty algebra, it's very convenient. See Olver's Asymptotics and Special Functions chapter on Liouville-Green transform and see what I mean :) –  Pragabhava Oct 3 '12 at 6:22
    
Might be. I don't have a copy at hand, but I prefer $2\Re z$ over $z + \text{c.c.}$. –  martini Oct 3 '12 at 6:24
    
It's just a matter of style I guess. I'd use the c.c. notation to imply that not much attention should be payed to that term, as is just the complex conjugate. I can say that -for me- this is not the case. –  Pragabhava Oct 3 '12 at 6:29
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.