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0
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1answer
49 views

How do people measure performance overhead?

How do people measure performance overhead? Whenever someone is bragging about how their program or application performs better than another, they talk about particular measurements, eg time, ...
0
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2answers
87 views

Quicksort's asymptotic performance for array of [50,…,50,100,…100]

Let's have an array where first half are of value 50 and the second half 100. What would be the asymptotic performance when sorting using Quicksort. I think it it should be $O(n^2)$ as for array of ...
1
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1answer
47 views

The theoretical upper bounds for duplicate detection in a set of objects?

I recently had a lengthy exchange with someone about the most efficient way to remove duplicates from a collection. The debate was mostly centered around the specific behavior of C# collections, such ...
7
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2answers
163 views

Fast hashing: combination of different techniques to identify changes in a file?

I want to create a fast way to detect whether a file might or might not be the same. For almost 100% sureness I would use an existing hash algorithm, e.g. SHA256. However, the files are expected to be ...
0
votes
1answer
41 views

Task Manager Performance tab in windows [closed]

I do not understand the following options in windows. Could any one explain
4
votes
2answers
79 views

How to avoid column wise access in matrix multiplication?

I know when we access elements in rows it will be much faster than if it is accessed column wise. In matrix multiplication one of the matrices must be accessed column wise. In GPUs with CUDA/OpenCL ...
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0answers
27 views

Applications affected by memory performance

I'm writing a paper on the topic of applications affected more by memory performance than processor performance. I've got a lot written regarding the gap between the two, however I can't seem to find ...
2
votes
1answer
74 views

Tree flattening with layout guarantees

I want to flatten a binary tree into a linear array, and I wonder if there are specific algorithms to improve locality in the linearized representation (for instance, ensuring that all data from the ...
4
votes
1answer
172 views

Performance of row- vs. column-wise matrix traversal

Scott Meyers describes here that traversing a symmetric matrix row-wise performes significantly better over traversing it column-wise - which is also significantly counter-intuitive. The reasoning ...
0
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0answers
24 views

What are these notations O(1)/O(n)/O(log n)? [duplicate]

I am a newbie here I recently read tutorials on java about collection framework. The time complexity of various objects in reading/writing data What does it mean? ...
0
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2answers
111 views

What does it mean when a computer runs 'faster'?

If you have two computers with only one thread, a and b. And computer a runs twice as fast as computer b. Does this mean that computer a and can do twice as many operations in a given time in ...
5
votes
1answer
168 views

Is the memory-runtime tradeoff an equivalent of Heisenberg's uncertainty principle?

When I work on an algorithm to solve a computing problem, I often experience that speed can be increased by using more memory, and memory usage can be decreased at the price of increased running time, ...
3
votes
2answers
222 views

How should I store and sort a large number of 64-bit integers?

I have about 500,000,000 64-bit integers, so these numbers could be very large. I want to sort them as quickly as possible. I have a couple of questions: What data structure do you suggest for ...
2
votes
2answers
98 views

Regarding to the speed of supercomputer

There seems to be a sense of competition in creating the fastest computer in the world, and I feel like technically you just have to continue increasing the core number to gain more flops, which is ...
2
votes
1answer
68 views

performance between the data structures

I have developed two existing data structures and I want to see their performances over a certain algorithm. In this case I use Dijkstra's algorithm with binary and Fibonacci heaps. Just to ask, if I ...
0
votes
1answer
19 views

VAR autoincrement with constant space consumption for super large tables

Assume there was a database system that had a data type called VARINT or some variant that allowed instead of fixed-length INTs ...
2
votes
1answer
47 views

Optimization of Hierarchical Data Propagation

I have a system in existence which works on parent-child model. They share common attributes, as they belong to same class. A parent can enforces certain data on any user selected attribute, and the ...
8
votes
3answers
353 views

Finding maximum and minimum of consecutive XOR values

Given an integer array (maximum size 50000), I have to find the minimum and maximum $X$ such that $X = a_p \oplus a_{p+1} \oplus \dots \oplus a_q$ for some $p$, $q$ with $p \leq q$. I have tried this ...
0
votes
2answers
115 views

How to determine the Utilization and Efficiency of a file server?

I have shown my work below for the problem and would appreciate if someone can let me know if I'm on the right track or point me in the right direction if not. An 8 processor file server handles a ...
2
votes
0answers
48 views

Determine interference factors in parallel computing

Parallel processes interfere with each other in many ways, by competing for shared resources such as shared caches, memory, disks, etc. Would it be possible to determine latent factors just with a ...
1
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0answers
30 views

How to generate inputs to evaluate the performance of an implementation?

How can we assert that the performance of an implementation matches the expected performance defined in terms of Big-$\mathcal{O}$ and friends by generating best/worst case inputs? I'm thinking of a ...
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2answers
742 views

How fast can we find all Four-Square combinations that sum to N?

A question was asked at Stack Overflow (here): Given an integer $N$, print out all possible combinations of integer values of $A,B,C$ and $D$ which solve the equation $A^2+B^2+C^2+D^2 = N$. ...
2
votes
1answer
1k views

Theoretical speed gain of quad core vs. single core

I first asked this question at cstheory, but they suggested to ask my question here, so here it goes ... I'm working on my masters thesis and I need to have theoretical value of the (average) speed ...
5
votes
3answers
2k views

A faster, leaner JavaScript for scientific computing: what features should I keep?

Here I'm really interested in lowering barriers to mathematical education. Target: I'd like to see created for the JavaScript community, an equivalent of the Python-based/linked scientific and ...