Array ( [0] => Array ( [title] => L22A [link] => https://www.youtube.com/embed/BKaIzegCC64 ) [1] => Array ( [title] => L22B [link] => https://www.youtube.com/embed/s_dSSY2YFdE ) ) 國立清華大學開放式課程OpenCourseWare(NTHU, OCW) - Lecture 22 | Variation-of-constant formula for linear discrete DDEs