Computer science or computing science (abbreviated CS or CompSci) is the scientific approach to computation and its applications.
4
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2answers
150 views
constraints in developing software
According to this
As opposed to the constraints in other kinds of engineering, where
the constraints of what you can build are the constraints of physical
systems, the constraints imposed in ...
0
votes
2answers
83 views
Formats for Storing Sparse Matrices
For storing sparse matrices I know there are multiple formats that are common, like COO, CSR, DIA, ELL, HYB, etc. (Link to some storage formats), but I haven't found that any of these stores the ...
1
vote
1answer
67 views
How to manage code experiments meant to stay permanently with git?
I have an asm/C code which implements some image filters. The objective of this project is experimentation with different implementations, benchmarking, plotting and reporting data to write a paper ...
1
vote
3answers
258 views
Find if any pair exists in an unsorted array?
I have come across a programming question in which I have to determine :
Does there exists at least one pair in a given unsorted array such
that
|i - j| <= K and |A[i] - A[j]| <= x
?
...
1
vote
1answer
25 views
Relation and difference between recursively enumerable languages and Turing complete languages?
From https://en.wikipedia.org/wiki/Recursively_enumerable_language
a formal language is called recursively enumerable (also
recognizable, partially decidable, semidecidable, Turing-acceptable or
...
0
votes
2answers
132 views
How to Create a Parser that Operates in Reverse
I've got my answer to this in the comment of the one I checked. Which Algorithm Approach Should I Take to Generate Lambda Expressions in Java? but I don't exactly know where to look in terms of ...
0
votes
1answer
140 views
Computational limits for huge k-th permutation?
Would it be feasible to calculate directly a k-permutation like k = 10^200000000?
If not,
What would be the computational limit to calculate huge k-th permutation in a today computer? How can I ...
1
vote
2answers
126 views
Having trouble with AP computer science sample test problem
I am currently taking AP Computer Science at my high school and while looking at some sample AP test problems I came across one that really confused me.
Sample Problem
The answer to the problem is ...
-1
votes
1answer
77 views
Why do we use 'assert not' in this example?
My code takes 2 dates and finds the age of those dates in days. In my daysBetweenDates method the instructor uses an assert statement:
assert not dateIsBefore(year2, month2, day2, year1, month1, day1)...
7
votes
2answers
213 views
How does sleeping a thread work?
When you sleep a thread, what is actually going on?
I see that sleeping a thread "pauses the current thread for a given period of time". But just how does it work?
According to How Thread.sleep() ...
10
votes
3answers
389 views
Why did Ruby creators had to use the concept of Symbols?
So, why did Ruby creators had to use the concept of symbols in the language?
I ask from the perspective of a non-ruby programmer trying to understand it. I've learned lots of other languages and ...
3
votes
3answers
358 views
Is it faster to make a dedicated variable instead of calling deeply nested object several times?
In a JavaScript app, suppose I have a nested object like this:
var myObject = {
someProp: {
someOtherProp: {
anotherOne: {
yetAnother: {
...
0
votes
1answer
61 views
Cyclomatic complexity - what exactly does the word “cyclomatic” mean?
I understand what cyclomatic complexity is, but I was trying to find the origin/meaning behind the word "cyclomatic" and could not find anything that wasn't about cyclomatic complexity. Does this ...
0
votes
1answer
24 views
What relationship describes two different abstractions of the same dataset
I am wondering if there is a specific term for when multiple representations are data equivalent. Meaning that you can transfer the data from one representation to the other without any loss of data.
...
1
vote
2answers
77 views
Language interaction
How does a program composed of several languages work? How do the languages work together or interact with each other? How do they understand stand each other? How do you know when to use any given ...
-1
votes
1answer
91 views
Floating point absorption phenomena and ULP
Numerical analysis text books talks about the absorption phenomena (Introduction to Numerical Analysis and Scientific Computing; Nabil Nassif; Dolly Khoueiri Fayyad; CRC Press; 2014) when adding ...
30
votes
13answers
3k views
Help in understanding computer science, programming and abstraction [duplicate]
Until now, I always believed that you should learn programming languages that make you do low-level stuff (e.g. C) to understand what's really happening under the hood and how the computer really ...
2
votes
2answers
232 views
Why are semantics and type systems are so important?
I heard that semantics and type systems are very important for all programmers! But I why are they so important? I don't understand. Maybe they are imortant only for theoreticians and compiler ...
0
votes
0answers
72 views
avoid nan and inf in floating point multiplication and division
I have the following hypothesis:
It is better to reorder mult and div operation in such a way that we can do our best effort to avoid nan, inf and operating with subnormals.
The reorder should follow ...
0
votes
1answer
58 views
Foundations of computation, and relation to modern computers [closed]
I want to understand how the theoretical foundations of computation relate to real-world computers. As far as my knowledge goes, Turing machines, recursive functions, finite state machines, lambda ...
2
votes
2answers
89 views
From a set of rules, derive the implications? [closed]
I've only just become interested in this domain, so sorry if I'm not using the correct terminologies.
What I want is the following: Say I have a set of rules (or constraints), I want to derive some ...
1
vote
2answers
449 views
How do Symbol Tables, Lexers and Parsers work together in a modern design? [closed]
I'm working on creating my own scripting language for learning purposes. I've been reading through the Dragon Book and some things are a little unclear to me regarding the Symbol Table as well as ...
0
votes
0answers
144 views
What is this compression algorithm? (Similar to RLE)
In Run Length Encoding (RLE), a large set of information is encoded by storing the quantity of consecutive sequences. A canonical example is:
...
31
votes
2answers
1k views
What is the meaning of “doesn't compose”?
I see a lot of texts, especially functional programming texts, claim that certain CS concepts "don't compose". Examples are: locks don't compose, monads don't compose.
I've been having a hard time ...
3
votes
4answers
574 views
How is a state machine different from any other computer program?
I have seen several implementations of "State Machines" on github. As far as I understand, a state machine takes input that may or may not transform its state into one of a finite set of other states. ...
0
votes
2answers
1k views
Is studying algorithms important for game development? [closed]
I am fairly new in the programming world, I have a 1-year experience and I learned by watching online courses, and I made few iOS apps.
Now I am moving into game development and I already ...
2
votes
1answer
117 views
Find all factors(prime and composite) of a number
We can find all the prime factors using a Sieve of Erastothenes. But how do we find ALL the factors of a number?
For instance, 24 = 2x2x2x3
But the complete factor list is - 1,2,3,4,6,8,12,24.
I am ...
12
votes
5answers
1k views
How come the computer doesn't have to read the entire table when the column is indexed? [duplicate]
Let's say a table with two columns has 100 quadrillion records. And I want to find a record that has column #2 equal something.
If column #2 is indexed it returns the result immediately, but if it's ...
3
votes
2answers
688 views
Looking for a DP algorithm for a specific packing problem
I have the following problem to solve:
Given a ferry with length d and a list of n cars conataining their length we must load the cars on the ferry in an order in which they appear in the list on 2 ...
2
votes
2answers
584 views
Finding common prefixes for a set of strings
I am trying to find common prefixes for a sorted set of strings. i.e. if the following strings are given:
AB123456
AB123457
ABCDEFGH
ABCDEFGX1
ABCDEFGY
XXXX
then my function should return three ...
2
votes
4answers
446 views
Should all programmers know how to solve algorithms, etc [closed]
I'm 15 and have been programming for about 3-4 years. I mostly program in Java as it was my first language.
I would like to be a programmer when I'm older, but I'm not sure about the differences. I'...
8
votes
2answers
2k views
What is the relationship between lambda calculus and programming languages? [closed]
I am starting my first year (in college) in Computer Science next year and I write mostly in C (if that is to matter). I have tried searching but most of what I find assumes knowledge of lambda ...
3
votes
2answers
2k views
What does 'upper bound' mean in context of BigO?
My computer science teacher says Big O has an upper bound but no lower bound. When I look at a graph of an algorithm mapped out using BigO though, there isn't an upper bound at all. The upper limit ...
11
votes
1answer
591 views
What Is λ-calculus essentially?
I have what I would call a philosophical question about λ-calculus.
When you explore λ-calculus you will be surprised to see all the things that you can do there. You can define integers, arithmetic ...
-1
votes
2answers
132 views
Is 'lazy' the correct term for timestamp-based skipping? [closed]
(1)
The oldmakeutility looks at timestamps, and if the output is newer than the input, it skips (pointless, time-consuming) re-compilation of e.g. C files.
The same is true for many languages and ...
0
votes
1answer
142 views
How are the conceptual pairs Abstract/Concrete, Generic/Specific, and Complex/Simple related to one another in software architecture?
(= 2 (+ 1 1))
take the above. The requirement of the '=' predicate is that its arguments be comparable. Any two structures are comparable in this case, and so the contract/requirement is pretty ...
0
votes
3answers
2k views
What is Atomicity?
I'm really struggling to find a concrete, easy to grasp, explanation of Atomicity.
My understanding thus far is that to ensure an operation is atomic you wrap the critical code in a locker. But that'...
1
vote
1answer
260 views
Which Computer Vision / Image Processing technique would solve light imbalance in images?
Given a colour image whose light intensity is dim at the edges and bright in the middle, such as [dim bright dim], which computer vision technique would be recommended to correct this imbalance? ...
1
vote
1answer
337 views
Can we still consider that Moore's law still holds true regarding the consequence on CPU speed? [closed]
Moore's law is an empirical law and in simple terms states that the number of transistors on integrated circuits doubles approximately every two years.
One of the consequences of Moore's law is that ...
0
votes
1answer
181 views
Difficulty implementing algorithms from abstract understanding [closed]
I've got decent programming experience for an undergraduate. I just started the study of algorithms. I read the description and saw visual examples that make perfect sense in my head. But when it ...
1
vote
4answers
340 views
What do you call a tree that grows in both directions? [closed]
What would be the technical term for a tree that grows in both the directions, starting from the root in the middle?
The central idea being that new elements can be added to the tree (Now, I am not ...
18
votes
6answers
2k views
What is an example of a computationally impossible business problem?
I have coworker who refuses to accept the reality that Turing machines (and Von Neuman machines by extension) cannot solve their own halting problem stating:
You can do anything with enough time ...
-2
votes
1answer
2k views
what is the difference between a software engineer and project manager? [closed]
I understand that a software engineers job is to work with all aspects of developing and supporting a software system. How does a project manager fit/work with a software engineer in a small team (5 ...
12
votes
1answer
332 views
What intermediate representations can be used to reason about concurrency?
I am trying to better understand what would be required for a compiler to be able to make intelligent choices regarding concurrency on behalf of the programmer. I realize that there are many difficult ...
2
votes
1answer
359 views
Implementation of chess endgame engine without Endgame Tablebases
I'm interested in creating an chess endgame solving engine.
The endgames in chess are usually solved using the endgame table-bases generated by retrograde algorithm.
I have found that Artificial ...
6
votes
2answers
805 views
Are there alternatives to stack+heap+static memory model?
All programs I have seen organize their data memory into one or more call stacks (usually fixed size, but sometimes not), the heap, and static memory. Lately thread-local static storage has been ...
2
votes
2answers
103 views
How is indirection different from aliasing?
Take from wikipedia, aliasing is defined as accessing a data location through different names.
Also taken from wikipedia, indirection is defined as referencing something "using a name, reference, or ...
4
votes
4answers
1k views
Why do some compilers generate direct machine code?
I was taking this course - CMU 18-447, Computer Architecture at Carnegie Mellon to brush my knowledge and concepts.
They say that most of the machine level details and implementations are taken care ...
2
votes
1answer
253 views
Resources for understanding a programming language and its specifications and grammar deeply [closed]
I'm a computer engineer and all the courses we have had about programming and computer languages were an introduction to C/Java and OOP. Now I feel like reading Java language specification to learn a ...
80
votes
11answers
7k views
How can I make sure that I'm actually learning how to program rather than simply learning the details of a language? [closed]
I often hear that a real programmer can easily learn any language within a week. Languages are just tools for getting things done, I'm told. Programming is the ultimate skill that must be learned and ...
