Questions tagged [optimization]

Optimization is the process of improving an existing program to make it work more efficiently or/and using less resources.

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How to optimize iterable queries with external arguments

I will use C# here as an example, but my question is about any language. My question is from framework to compiler perspective (i.e the solution can be by implementing given idea inside compiler) ...
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2answers
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Optimization problem where to start, what algorithms to use? [closed]

I have an optimization problem and I was wondering where to start from to be able resolve it. I think it can be solved with an NP-complete algorithm but I am not sure where to start from. The problem ...
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1answer
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Improving sampling algorithm

I am having a bit of trouble designing a new feature at the moment. It is part of a resource management system. I was wondering if anyone has experience doing anything similar. I'll try to explain: ...
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3answers
735 views

What can qualify for potential tail call recursion (TCO) optimization or tail recursion elimination (TRE)

Short question is: what can qualify for potential tail call recursion optimization (TCO) or tail recursion elimination (TRE) if the compiler or interpreter supports it. The summary of this question ...
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0answers
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Program to select N integers with constraints [closed]

I need to write a program which takes 4 inputs as follows N = The number of integers to be generated (10 < N < 10000) Start = The minimum value of the integers (100 < Start) End = The ...
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1answer
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Maximizing Value and Volume, minimizing weight - Knapsack

Trying out a Knapsack variant where the rules are Any item you take must fit completely in the bag Usable metrics of the bag are length(l),width(w),height(h) and you can assume that if the products ...
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1answer
791 views

How to safely and cheaply delete a directory's contents that are constantly being deleted/overwritten

I'm coding something that will check a specific static location's directory, and if it exists, and a certain process has not run in n minutes, it deletes that directory's files and all sub-directory ...
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1answer
493 views

Combinatorial Optimization: Filling a Bag with Sand

I have an interesting "real-world" combinatorial optimization problem that I need to solve programmatically, however I have yet been able to whiteboard a good strategy. The task is similar to the ...
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1answer
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Sorting an array based on another array's order, quickly [closed]

There are two arrays of maps. The first array contains maps of ID values in a specific order (but not necessarily either pure ASC or DESC ordering): // pseudo code first := [ {"id": 1}, {"...
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1answer
376 views

Optimization: How much time saved is considered worth it? [closed]

I was reading up about branch predictions and cache misses, and have decided to read what every programmer should know about memory. But I'm not sure how much low level knowledge do I need to have to ...
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1answer
110 views

Multiple variable assignment vs HashTable lookup

I'm writing a CUIT ( Coded UI Test ) and I'm replacing variables with data fetched from a csv. Example: this.UIMap.IDBParams.UITboxFsEditText = TestContext.DataRow["num_fs"].ToString(); this.UIMap....
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1answer
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storing single character value use string or int C# [closed]

While storing single character value for the purpose of status, gender, delete_flag etc. which is better data type string or int. Suppose :: status = A/I or status = 1/0 gender = M/F or gender = 1/0 ...
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Do nested conditionals have a significant performance impact? [duplicate]

This is a question that lives in my mind from a long time. Does the use of multiple nested conditional statements impact the performance of a taken code? So far I know that programmers have created a ...
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2answers
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How to distribute a number of elements in a bucket so that it is within a range?

I have 50 elements n1, n2, n3, ... , n50 and a limited number of buckets, say 5 buckets and each bucket can hold a range from, say 100 to 150 only (which is nothing but the sum of the elements in that ...
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Cost of cache coherency/sharing data across multiple cores?

If I have two CPU cores, one is writing a particular cache line and the other core wishes to Read Write the same cache line, what are the costs (in cycles) for doing so? I am a little unsure ...
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Premature memoization on obvious cases

In the code below there will be several instances of MainClass. class MainClass(object): def f(self, x): # expensive operations. # ... return 'something' Each instance ...
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3answers
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Linking two or more different programming languages

I would like to ask how optimizer software written in C/C++ can be linked to simulator software written in FORTRAN or any other language. I have copied the section of journal article of Singh and ...
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2answers
128 views

How do you avoid dominant solutions in multi-objective simulated annealing?

Imagine an RPG game were you can cary N items, and you want to maximise your damage, attack speed and armour, given a set of items. I implemented simulated annealing where a permutation simply ...
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Can a pimpl variation be implemented without any performance penalty?

One of the issues of pimpl is the performance penalty of using it (additional memory allocation, non-contiguous data members, additional indirections, etc..). I would like to propose a variation on ...
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1answer
333 views

Optimizing instant notifications

Scenario To deliver instant notifications to the client, I'm sending an AJAX request to a PHP page that checks if there are new notifications: if there are, it outputs them, otherwise it sleeps for ...
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1answer
177 views

Can fast, optimized server calls collapse a server?

I've followed a series of optimizations to make our APIs faster. We microoptimized a lot of PHP code to faster, native methods, we unset variables where they were not being used anymore, and basically ...
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3answers
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My algorithm that extracts the largest box that can be made from smaller boxes, is too slow

Imagine a cube based world (such as Minecraft, Trove, or Cube World) where everything is made up of identically sized cubes and all the cubes are of the same kind. The goal is to represent the world ...
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2answers
302 views

Reducing a sequence of array modification operations (insert, sort, replace, remove)

Given a plain array of values, e.g. ["Apple", "Orange", "Banana", "Strawberry"] and a list of operations from the set of [insert, delete, sort and replace], e.g. [ {cmd: "insert", index: 2, ...
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Work out which parcel deliveries we ship ourselves and which we outsource

Firstly, I hope I'm asking this in the right place. I work for a large online retailer in UK. We ship approaching 2000 orders each day and are growing very quickly. We currently use multiple delivery ...
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Feasible solution on the constructions phase of GRASP

I am learning about the GRASP (Greedy Randomized Adaptive Search) meta-heuristics. From what I understood, GRASP is based on two main phases. The first one: Construct a initial solution based on a ...
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1answer
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Is serving a single document from a server to a browser slower than serving multiple documents?

I was looking into how to optimize web pages and the biggest way (code-wise) to optimize a website is to reduce the number of requests a browser has to make to your web server to get the full page. ...
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2answers
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Algorithm for comparing hundreds of similar, but not identical documents

I have seen similar questions about text comparison, but none on such a large scale. I have a client with two sets of recordings of speeches, 250 and 550 recordings each. Each of the recordings in ...
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0answers
145 views

Optimizing trigram look ups with wildcards

I am working on creating a spell-checking service for Android (note: this is a platform- and language-neutral question) for Asturian, a minority Romance language. We're using hunspell as the base but ...
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417 views

Does loop unrolling on a JIT platfrom (.NET or JVM) provide any benefit

I know in C, you can use loop unrolling (unwinding) to help reduce branching in your code but at the expense of program size. That seems to work when you compile to a target machine, however, does it ...
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1answer
583 views

Why is Haskell unable to avoid repeated evaluation without the monomorphism restriction?

I just finished learnyouahaskell the other day, and I was trying to make sense of the Monomorphism Restriction, as described by the Haskell Wiki. I think I understand how the MR can prevent repeated ...
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596 views

Android runtime - does ART miss optimization opportunities over Dalvik?

Is ART a strict improvement over Dalvik, or there are optimizations that an ahead-of-time compiler will miss compared to JIT, but Google decide they don't matter in practice? For example, with JIT, ...
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6answers
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performance versus reusability

How can I write functions that are reusable without sacrificing performance? I am repeatedly coming up against the situation where I want to write a function in a way that makes it reusable (e.g. it ...
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2answers
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Ant colony algorithm

I am a student working on an ant colony simulator for a course project. The algorithm for it is (obviously) an ant colony algorithm. I know there are various forms of the algorithm but all of those ...
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1answer
294 views

Different Implemenations of Tail Call Optimisation

I've heard some people in my university discuss the tail call optimisation in ML as if it were a special version tail call optimisation. Does the ML (SML/F#) implementations of tco in these languages ...
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6answers
14k views

How does branch prediction work, if you still have to check for the conditions?

I was reading the popular answer about Branch Prediction from https://stackoverflow.com/q/11227809/555690, and there is something confusing me: If you guessed right, it continues on. If you ...
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1answer
3k views

How to merge two functions that do same things with different variables

I have these two Javascript functions that are equal except for the variables onClickVoteUp: function (e) { var $target = $(e.target); var upvoted = this.model.get("upvoted"); var ...
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2answers
264 views

Do today's modern compilers perform run time checks?

This is regarding compilers. Do compilers perform run time dependency checks to decide to vectorize a loop ? In other words, do compilers trace through the logic as it would in run-time to ...
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0answers
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A fast algorithm for a simple multi-objective minimization?

I have a set of n (arbitrary) integer numbers S which I want to partition into k subsets S_i each of size n/k (you can assume that k divides n). Let A be the arithmetic mean of elements of the set S. ...
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Loop Unfolding and Named Significant Bits

I've been writing a Parser Compiler for the last seven or so years, and I recently got to the point (yet again, never satisfied) of structuring the portion dealing with the portions of the language ...
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2answers
122 views

When, if ever, are basic concurrency optimizations generally made?

Lets say I need to preform the following computationally intensive task For i in range(100000000): doComplexCalculationWithNoSideEffects(i) Most people I talk to tell me that basically any ...
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1answer
307 views

One Script file or Multiple Script Files [closed]

I have a moderately long(for me at least) bash script file that that maintains a list of LAN users and the bandwidth each one uses. It is 199 lines with 11 functions and is already calling 3 different ...
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2answers
184 views

Should benchmarks (to compare processors performance) be compiled with optimization CFLAGS?

I need to compare performance of 2 processors and I concluded I should benchmark then with several various tests. I'm currently using linpack (HPL) (because it's still well known and used for ...
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2answers
2k views

get All data vs get partial data Optimization

Let's say a client makes a GET call to the server to get all the followers of some user. now the client shows a list of all the followers but the only data the list needs is: {"username" : "user", "...
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1answer
122 views

Deciding How To Split Up Architecture Using If Blocks

I'm having trouble deciding the best way to handle splitting up if block checks for different architectures. I may be handling the scenario completely wrong, so let me know if that is the case, or if ...
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1answer
1k views

In C#, performance wise, an object's size does matter when you access one of its members through a reference?

It may be a stupid question but in C#, performance wise, an object's size or complexity does matter when you access one of its members through a reference? Or only that specific member is all that ...
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2answers
275 views

When should we work on GC optimization? [closed]

So, I've learnt about how GC works and how can I monitor it via VisualVM, but my question is about why we should ever perform GC optimization? In our web project (JSF/Spring/Hibernate) we haven't ...
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4answers
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Maintenance cost of SIMD programming code base

Question: The software industry's consensus is that clean and simple code is fundamental to the long-term viability of the code base and the organization that owns it. These properties lead to lower ...
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3answers
276 views

Best approach for storing huge data

I'll be handling 300,000+ users. Each user (after logging in) will be able to create lets say "folders", in each folder, users will create "name=value,name2=value2,name3=value3" entry pairs. Each name ...
4
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1answer
29k views

Designing a scalable schema for college database [closed]

I am trying to build back end for college ERP system. The system will be based on LAMP. These is the scenario: Colleges have 5 branches There are 4-6 classes in each branch. There are 80 students ...
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0answers
767 views

Algorithm for sport tournament bracket tree

I would like to develop a library that: receive n players in input response with the tournaments brackets in output. I would ask you what kind of algorithm I have to use to choose the correct tree ...

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