some functions define rng internally

as per title, is this a good idea?

• recode
• linalg::Matrix::random
• a bunch of tests
• the main

changed title from some functions defined rng internally to some functions define rng internally

changed the description

mentioned in issue #7 (closed)

mentioned in merge request !65 (merged)

mentioned in commit fc23965a

closed in !65 (merged)

closed