The focus is on most powerful paradigms and techniques of how to design algorithms, and measure their efficiency. The topics will include hashing, sketching, dimension reduction, linear programming, spectral graph theory, gradient descent, multiplicative weights, compressed sensing, and others. Srinivas Devadas and Prof.
Given a picture of the back of a book taken with a camera phone, we could use this to extract its ISBN number. A little bit about barcodes The vast majority of packaged and mass-produced consumer goods sold have a barcode somewhere on them.
Although there are dozens of barcode systems used across a variety specialised domains, consumer products typically use either UPC-A or EAN In fact, UPC-A has been officially declared obsolete sincethough it's still widely used within the United States.
This neatly reduces our descriptive problem to one standard. As the name suggests, EAN describes a digit sequence, which is Okasaki thesis into four groups. The first two digits describe the number system. This can either indicate the nationality of the manufacturer, or describe one of a few other categories, such as ISBN book identifier numbers.
The next five digits are a manufacturer ID, assigned by a country's numbering authority. The five digits that follow are Okasaki thesis product ID, assigned by the manufacturer.
Smaller manufacturers may have a longer manufacturer ID and shorter product ID, but they still add up to ten digits. The last digit is a check digit, allowing a scanner to validate the digit string it scans.
The only way in which an EAN barcode differs from a UPC-A barcode is that the latter uses a single digit to represent its number system. The system used by EAN is a little involved. We start by computing the check digit, which is the last digit of a string.
The computation proceeds from the right of the string. Each successive digit is either multiplied by three or left alone the cycle function repeats its input list infinitely. The check digit is the difference between their sum, modulo ten, and the number ten.
A run of the same digits thus looks like a thicker bar. The sequence of bits in a barcode is as follows. The leading guard sequence, encoded as A group of six digits, each seven bits wide. Another guard sequence, encoded as A group of six more digits.
The trailing guard sequence, encoded as The digits in the left and right groups have separate encodings. On the left, digits are encoded with parity bits. The parity bits encode the 13th digit of the barcode. Introducing arrays Before we continue, here are all of the imports that we will be using in the remainder of this chapter.
Char digitToInt import Data. List foldl', group, sort, sortBy, tails import Data. Maybe catMaybes, listToMaybe import Data. Ratio Ratio import Data.
Word Word8 import System. Environment getArgs import qualified Data. Char8 as L import qualified Data. Map as M import Parse -- from chapter 11 The barcode encoding process can largely be table-driven, in which we use small tables of bit patterns to decide how to encode each digit.
Haskell's bread-and-butter data types, lists and tuples, are not well suited to use for tables whose elements may be accessed randomly.Port Manteaux churns out silly new words when you feed it an idea or two.
Enter a word (or two) above and you'll get back a bunch of portmanteaux created by jamming together words that are conceptually related to your inputs.. For example, enter "giraffe" and you'll get . User Review - Flag as inappropriate This is a great book.
An improved version of Okasaki's PhD thesis, the book introduces the reader to the notion of efficient data structures which still get to be purely functional (i.e.
not imperative, no side-effects). A common problem with purely functional data structures is that, since there is no state, 4/5(5). Feb 19, · In , I published a book called Purely Functional Data leslutinsduphoenix.com years later, the book is still selling well.
(Every time I get a royalty check, my wife the skeptic says “People are still buying that?!”) The ten-year anniversary seems like a good time to reflect back on my experience with this book.
Chris Okasaki's thesis was published long before either of those languages were developed, and studied closely by programmers across a great variety of functional languages such as Haskell, the MLs (all examples in the thesis are in Haskell and SML), surely CLISP coders, Erlang, and any other language you can figure has an interest in.
Looking for books on computer algorithm? Check our section of free e-books and guides on computer algorithm now! This page contains list of freely available E-books, Online Textbooks and Tutorials in computer algorithm.
In computer science, a purely functional data structure is a data structure that can be implemented in a purely functional language. The main difference between an arbitrary data structure and a purely functional one is that the latter is (strongly) immutable.