# I don't understand convolution, and I would love to see some worked examples

I'm trying to get ahead on my classes for the school year and decided to start with Alan Oppenheim's Signals and Systems course. I'm already very stuck on how to convolve two signals. I have some specific examples from his textbook that I would love to see worked in order to get a better understanding. The answer I get is different from the answer the book gives. I tried to graph both of these, and then shift h[n] through x[n] and calculate each point. However, this does not give the book's result of Secondly I don't understand this problem Any explanations or clues to understanding would be appreciated. I've been watching different videos and searching around and something just isn't clicking.

Below is my attempt to solve the first. I only had blue and black ink for the graphs, and it's not easy to see the different between the h[n] and x[n] graphs.

• "The answer I get is different from the answer the book gives", it's always better if you show us your attempt so we can see exactly where things went wrong. Then we'll be able to see/give exactly what kind of help you need to get to the correct answer. - Also, is it the mathematical part about convolution that you have trouble with? Or is it the entire meaning of convolution, like what it is and why it's used? – Harry Svensson Jul 20 '18 at 2:47
• sites.google.com/site/butwhymath/m/convolution – BeB00 Jul 20 '18 at 2:59
• Show your complete working/solution - as Harry asked you earlier - then people may help you. – Solar Mike Jul 20 '18 at 5:01
• @BeB00 Woaw. I'm fairly knowledgeable about what convolution is (1D), but that site confused me with 2D convolution. – Harry Svensson Jul 20 '18 at 9:12

## 1 Answer

First off, visualizing how these this function works graphically can be a big help. The first function is 'slid' past the second function, the area of the two defines the height of the third function

Hint: Sometimes its best to draw the functions, a dirac delta function times a dirac delta function is dirac delta function (and dirac delta functions simply copy whatever function they are convoluted with) 