When i was in 1st semester of Engineering, I heard about "filters"a lot like how difficult it is and bla bla n bla. By then, we had studied filter too. And it was quite easy. Lpf(low pass filter), Hpf(high pass filter), Bpf(band pass filter) and I used to wonder how complex could this be, why is it such a topic of discussion among the 4th year students. Yesterday, me n my friend, we studied from 9am to 4pm almost continuously and all we could cover was 5 hellish pages and I swear there was more than 50% of the things we found out we have to learn by heart and there is no any other way out. All this because there is a subject "filter" which is not in our syllabus but again there is a subject named "DSAP" which is father of great grand father of toughest subjects which is in our syllabus and we have to have a good knowledge of Fourier transform, convolution, etc etc and not to forget "filter" to understand its course of contents. But how are we supposed to have any knowledge about a subject we have never studied? And its not a story book but just derivations, derivations and formulas. It would have been a help if we had a good tutor, but no lying all that our so called teacher did was speak some foreign language(out of the world language) that was impossible to get. Any question we asked, the answer would be same: " you have studied about it in previous class, turn the pages and see for it" or "don't you study at home??" or the most famous one "we will talk about this in the numerical". 3 days and 7 hours and still DSAP is a subject of question mark.