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.

Am reading about Reproducing Kernel Hilbert Space(RKHS) while reading through Functional Analysis and Hilbert Space material and am unable to get the notation :

$k(·,xi)$ correctly. What does the dot '.' signify? $k$ is a p.s.d kernel and $xi$ is a point in real space. I have a background in linear algebra, statistics and advanced calculus.

share|improve this question
add comment

1 Answer 1

The dot is a place holder for an appropriate variable. You may have seen this before when denoting inner products $ \| \cdot \|$.

share|improve this answer
So, is $k(·,xi)$ a vector, with the placeholder taking all the elements in a vector $x$ other than $x_i$? –  qlinck Oct 20 '12 at 20:01
add comment

Your Answer


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.