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justinmeiners / efficient-programming-with-components

Course notes for Alexander Stepanov's teachings on design and usage of C++ STL.
https://www.jmeiners.com/efficient-programming-with-components/
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10 clarifications #47

Closed justinmeiners closed 2 years ago

justinmeiners commented 2 years ago
justinmeiners commented 2 years ago

@aharrison24 Here is an initial pass which mostly fixes typos and footnotes with your recommendations. I am still working on the larger reorg!

Please bring them up if you think things should be different. I think everything we talked about, but I did remove some details from the Dirichlet proof footnote.

aharrison24 commented 2 years ago

I've gone ahead and read chapter 11 and had a good think about the algorithm. I think I have a reasonable understanding of what's going on now. There are certainly some things I would have appreciated knowing sooner. I've mentioned most of them in my in-line comments.

A couple of minor extra things: In the add_to_counter algorithm it would be helpful to clarify that carry is the element to be inserted and op is a binary operation such as min or max that returns one of its two inputs.

I also think it would be very valuable to have a slightly extended example of how the counter works, where multiple elements are inserted. You could do an example where the elements are characters and the binary operator is min, for instance. 'zero' could be a space character. You could push in 8 letters in an order that causes multiple slots to be occupied at the end. You can use that to show that the counter only needs log2(8) = 3 slots. You can also show that after all the elements have been inserted, the job isn't yet finished. This justifies the need for the reduce_counter operation, which performs all the remaining comparisons to get to a single 'winner'. I think that's important, because with the text as it is currently, the reduction step is never really justified. It's just presented as something that is necessary.

aharrison24 commented 2 years ago

I also realised that nowhere is it explicitly stated that the counter starts out empty and has elements pushed in to it one at a time.

justinmeiners commented 2 years ago

I just finished the "big" revision and I think I have been able to address most of your comments. I went back to the videos to review this section and found some helpful comments I missed which address many of your concerns.

I have added comments to this code here indicating specific resolutions to concerns. Once again, I really appreciate you working through this with me.

justinmeiners commented 2 years ago

it would be very valuable to have a slightly extended example of how the counter works

I think that's a great idea, and added it to issue #48 .

justinmeiners commented 2 years ago

I have resolved those comments you left. I am going to merge this in for now as it is a significant improvement. Let's start a new PR for additional fixes if needed. (I will review your issue again.)