On Fri, Nov 29, 2013 at 10:16 PM, Amit Nithian <anith...@gmail.com> wrote:
> Hi Ted, > > Thanks for your response. I thought that the mean of a sparse vector is > simply the mean of the "defined" elements? Why would the vectors become > dense unless you're meaning that all the undefined elements (0?) now will > be (0-m_x)? > Yes. Just so. All those zero elements become non-zero and the vector is thus non-dense. > > Looking at the following example: > X = [5 - 4] and Y= [4 5 2]. > > is m_x 4.5 or 3? 3. This is because the elements of X are really 5, 0, and 4. The zero is just not stored, but it still is the value of that element. > Is m_y 11/3 or (6/2) because we ignore the "5" since it's > counterpart in X is undefined?. > 11/3
