Security hacker computers and computer networks, and that cracker is the more appropriate term for those who break into computers, whether computer criminal (black hats) or computer security expert (white hats). A 2014 article concluded that "... the black-hat meaning still prevails among the general public". In computer security, a hacker is someone who focuses on security mechanisms of computer and network systems. While including those who endeavor to strengthen such mechanisms, it is more often used by the mass media and popular culture to refer to those who seek access despite these security measures. That is, the media portrays the 'hacker'
Prefix sum are calculated in the first pass on each processing unit; the prefix sum of these partial sums is then calculated and broadcast back to the processing units for a second pass using the now known prefix as the initial value. Asymptotically this method takes approximately two read operations and one write operation per item. When a data set may be updated dynamically, it may be stored in a Fenwick tree data structure. This structure allows both the lookup of any individual prefix sum value and the modification of any array value in logarithmic time per operation.. However, an earlier 1982