What is the advantage of the paperboat format in performance optimization of ML?
optimization,machine-learning,dataset
I don't know if this format really provides better representation, but I can speculate why it can be more efficient. First, as they state at format description, "Having data of the same precision consecutive enables hardware vectorization."; consider also wikipedia: "Vector processing techniques have since been added to almost all...
Better to declare JavaScript Object inside for loop or outside in terms of time optimization
javascript,arrays,optimization,variable-declaration
Both are the same. for loops don't create a new scope so the variables are hoisted to the top of the containing function scope. ex: > i undefined > for (var i = 0; i < 5; i++) { var test = i; } undefined > i 5 > test...
SAS drop multiple variables indexed by tens
If the var<xx> variables are all multiples of ten, i.e. there are no other variables beginning with var, you can use the colon-operator, which acts as a wildcard, e.g. drop var: ; /* drop all variables beginning with 'var' */ Alternatively, you can dynamically generate a list of all the...
How to improve performance method GetThumbnailAsync in window phone 8.1
c#,image-processing,optimization,winrt-xaml
You are currently awaiting file.GetThumbnailAsync for each file which means that although the function is executed asynchronously for each file, it is executed in order, not in parallel. Try converting each async operation returned from file.GetThumbnailAsyncto a Task and then storing those in a list and then await all tasks...
One-dimensional binpacking algorithm with relative costs
algorithm,optimization,bin-packing
If the problem under consideration is the generalized assignment problem, it is NP-hard but admits an approximation algorithm. From a brief look, the approximation ratio depends on the approximation ratio of an approximation algorithm for the knapsack problem, which in turn admits a fully polynomial time approximation scheme. In total....
OpenCV FAST corner detection SSE implementation walkthrough
c,performance,opencv,optimization,sse
As harold said, delta is used to make unsigned comparsion. Let's describe this implementation by steps: __m128i x0 = _mm_sub_epi8(_mm_loadu_si128((const __m128i*)(ptr + pixel[0])), delta); __m128i x1 = _mm_sub_epi8(_mm_loadu_si128((const __m128i*)(ptr + pixel[4])), delta); __m128i x2 = _mm_sub_epi8(_mm_loadu_si128((const __m128i*)(ptr + pixel[8])), delta); __m128i x3 = _mm_sub_epi8(_mm_loadu_si128((const __m128i*)(ptr + pixel[12])), delta); m0 =...
Minimize a function with two variables
There are a few problems with your overall process that cause trouble. First of all as @user227710 mentions in the comments you should replace && with &. These have different meanings. Now for the optimiser It looks like you want to set limits to your parameters (i.e. what is known...
How to write Max(L)<1 without using MAX func in MATLAB
every element of the vector L must be less than or equal to 1. This should be written as a set of constraints, not a single constraint. Artificially bundling the constraints L(1)<=1, L(2)<=1, ... into one constraint is just going to cause more pain to the solver. Example with...
(WHY?) Greatest+Coalesce way faster than a single select with or
(GREATEST and COALESCE are not relevant to the real question.) It may or may not be faster. Here's the logic... OR usually eliminates using an index. SELECT ... ORDER BY indexed_column LIMIT 1 may be able to use indexed_column to find the 1 row you want with no extra effort....
Which way of setting fields value is better and why?
Way 2 is better because it gives you a unified way of setting a variable value. But it brings in a risk, because you're calling an overrideable method in a constructor. So the right syntax is using the final keyword: public final void setField(int field){ this.field = field; } //way...
Minimum difference between sum of two numbers in an array
c++,algorithm,optimization,dynamic-programming
First of all, you are right that iteratively combining the best remaining student with the worst remaining student gives you the optimum result (see proof below). However, you don't calculate the cost of that solution correctly. You have to run through all pairs of your combination in order to find...
Why is Java faster if it repeats the same code?
java,optimization,jvm,jvm-hotspot
The fact that what you see is the result of some JIT optimization should be clear by now looking at all the comments you received. But what is really happening and why that code is optimized always nearly after the same amount of iterations of the outer for? I'll try...
Perform integer division using multiplication
assembly,optimization,bit-manipulation,division,multiplication
That method is called, "Division by Invariant Multiplication". The constants that you're seeing are actually approximates of the reciprocal. So rather than computing: N / D = Q you do something like this instead: N * (1/D) = Q where 1/D is a reciprocal that can be precomputed. Fundamentally, reciprocals...
How do i pass input variable to a C++ class method invoked in many places based on user input?
How about you use a switch/case structure to determine which function to call and what value of y to use? returnType (func*)(); // Create a function pointer and use that switch(userInput){ case 0: func = &func1; y = 5; case 1: func = &func2; y = 6; } To simplify...
Vary coefficient in system of equation in Matlab's fsolve
You can do it in one line using arrayfun, though it looks kind of convoluted and simply looping over p might be faster: function F = myfun(x,p) F = [p*x(1) - x(2) - exp(-x(1)); -x(1) + 2*x(2) - exp(-x(2))]; p_values = -3:.1:3; x = arrayfun(@(p)fsolve(@(x)myfun(x,p), x0), p_values, 'UniformOutput', false) and...
Does compiler optimize operation on const variable and literal const number?
You have some good answers already that answer your factual question: No, the C# compiler does not generate the code to do a single multiplication by 86. It generates a multiplication by 43 and a multiplication by 2. There are some subtleties here that no one has gone into though....
How does GCC store member functions in memory?
c++,performance,gcc,optimization,compiler-optimization
For the purpose of in-memory data representation, a C++ class can have either plain or static member functions, or virtual member functions (including some virtualdestructor, if any). Plain or static member functions do not take any space in data memory, but of course their compiled code take some resource, e.g....
Django query is slow, optimize
jquery,mysql,sql,django,optimization
Have you tried using Django pagination to set the result size? If not I'd say take a look at https://docs.djangoproject.com/en/1.8/topics/pagination/ Here's the long and short of the Doc as it pertains to you: from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger def listing(request): contact_list = Contacts.objects.all() paginator = Paginator(contact_list, 25) # Show...
Optimal Compare Algorithm for finding string matches in List of strings C#
c#,string,algorithm,optimization,language-agnostic
I decided to add this answer not because it is the optimal solution to your problem, but to illustrate two possible solutions that are relatively simple and that are somewhat in line with the approach you seem to be following yourself. The (non-optimized) sample below provides an extremely simple prefix...
How to make faster queries on my mysql table?
mysql,optimization,query-optimization
It is not possible to optimize a mixture of ASC and DESC, as in ORDER BY t.fecha DESC, t.idsensor ASC You tried a covering index: INDEX `sensor_temp` (`idsensor`,`fecha`,`temperatura`) However, this covering index may be better: INDEX `sensor_temp` (`fecha`,`idsensor`,`temperatura`) Then, if you are willing to get the sensors in a different...
How to efficiently select neighbour in 1-dimensional and n-dimensional space for Simulated Annealing
java,algorithm,search,optimization,simulated-annealing
So you are trying to find an n-dimensional point P' that is "randomly" near another n-dimensional point P; for example, at distance T. (Since this is simulated annealing, I assume that you will be decrementing T once in a while). This could work: double[] displacement(double t, int dimension, Random r)...
Performing large queries on Array or DB in php? [closed]
php,mysql,arrays,performance,optimization
Database connections are going to be the most expensive part of the algorithm, so minimize the amount of time each connection will last. Pull it from the database and loop through the array. Unless you are doing a function that would be very quick in a database (ie- sorting on...
Absolute value equality of variables in MATLAB optimization
It is not a convex problem, hence it cannot be solved directly with the tools you mention. It is inherently combinatorial, in the sense that you can enumerate cases based on the sign of the two variables, and for every such case, a linear equality holds. Hence, you can either...
Fair timing of two equivalent functions with -O3
Create a variable dummy and initialize it to argc. Then in each loop increment dummy by the return of the function. Then return dummy. This should stop the compiler from eliding the function calls.
MatLab code speed and optimization. How to improve?
performance,matlab,function,optimization,plot
The cost is coming from the calls to hermiteH -- for every call, this creates a new function using symbolic variables, then evaluates the function at your input. The key to speeding this up is to pre-compute the hermite polynomial functions then evaluate those rather than create them from scratch...
JQuery Show Hide Multiple Div Button
javascript,jquery,performance,function,optimization
Using your HTML with only two buttons and identical CSS The following JS works for better for me: Javascript: var newsDepth = 3; var maxNewsDepth = 3; $('#show-more-news').hide(); $('#show-more-news').click( function () { (newsDepth < maxNewsDepth ) && newsDepth++; $('#art-' + newsDepth).show(); $('#show-less-news').show(); if (newsDepth == maxNewsDepth) $('#show-more-news').hide(); }); $('#show-less-news').click( function...
type conversion performance optimizable?
c#,xml,csv,optimization,type-conversion
IEnumerable<string> values = new List<string>(); values = … Probably not going to be a big deal, but why create a new List<string>() just to throw it away. Replace this with either: IEnumerable<string> values; values = … If you need values defined in a previous scope, or else just: Enumerable<string> values...
Eager Loading Optimization in ruby on rails
ruby-on-rails,ruby,optimization,query-optimization
Your code isn't using the eager loaded data which is why adding includes is slowing things down - it's just extra work. In general if you call query methods ( where, order, etc) rails can't use the eager loaded data. Instead you can make a new association: has_many :active_variants, ->...
Efficiently transferring elements between arrays
javascript,arrays,optimization,memory-management,data-structures
splice is pretty harmful for performance in a loop. But you don't seem to need mutations on the input arrays anyway - you are creating new ones and overwrite the previous values. Just do function doTransfers() { var A_pending = []; var B2_pending = []; for (var i = 0;...
How can I minimize this function in R?
r,function,optimization,mathematical-optimization
I think you want to minimize the square of a-fptotal ... ff <- function(x) myfun(x)^2 > optimize(ff,lower=0,upper=30000) $minimum [1] 28356.39 $objective [1] 1.323489e-23 Or find the root (i.e. where myfun(x)==0): uniroot(myfun,interval=c(0,30000)) $root [1] 28356.39 $f.root [1] 1.482476e-08 $iter [1] 4 $init.it [1] NA $estim.prec [1] 6.103517e-05 ...
Java: Assigning a variable its current value?
java,variables,optimization,value
the cost of calling the method isEmpty() (allocating new space in the thread stack etc) negate any gains. if you want to assign an empty String to the variable, its most efiicient to do so without the if statement.
code optimising for if-else function
Here is an answer. First remove all the branches and then implement as SSE. I haven't check the speed yet. const int T1 = 17560; const int T2 = 244583; const int SHIFT = 16; int A = 2*((dx ^ dy) >= 0)-1; //check (dy,dx) opposite sign dy = abs(dy);...
(Java) Efficiency in my Starter Bubble Sort
java,algorithm,optimization,foreach,bubble-sort
Using indexOf is not correct, if your ArrayList x contains more than one value of i, your sort method will behave incorrectly. For example, this case: [5, 5, 1] After running your program, return [5, 5, 1] Plus, using indexOf, as mentioned by tucuxi, will slow down your program....
Optimizing a simple linear curve (constant and coefficient estimated from a regression)
If the functions are linear, then they will be at a minimum at the lower end of the range where beta>=0, and at the upper end of the range if beta<=0 - no need to use optimize(). It's not entirely clear what you're expecting the code to do - if...
Optimizing a large if-else branch with binary search
c,optimization,binary-search,linear-search
You should look at the generated instructions to see (gcc -S source.c), but generally it comes down to these three: 1) N is too small. If you only have a 8 different branches, you execute an average of 4 checks (assuming equally probable cases, otherwise it could be even faster)....
How to interpret the output of the CPLEX interactive optimizer?
The % gap is the relative difference between the best solution and the best known bound for a solution. This is guaranteed to be higher than the gap between the best known solution and the true global optimum. In your case, the best bound is 83.9275, the best bound is...
What is the most efficient way to perform a multiplication?
Here is a JMH benchmark: @OutputTimeUnit(TimeUnit.SECONDS) @BenchmarkMode({ Mode.Throughput }) @Warmup(iterations = 10) @Fork(value = 1) @State(Scope.Benchmark) public class MyBenchmark { private static final double CONSTANT = 1.6712 * 1000 * 60; private double x = 0; @Benchmark public void testCaseOne() { for (double i = 1; i < 1000_000; i++)...
Is there a more efficient way to solve this?
python,python-2.7,optimization,matrix
In terms of refactoring, you almost certainly want to avoid "brute force" in the sense of having to explicitly type out all your cases :) @alexmcf addresses this above. In conceptual terms, your approach follows the problem statement directly: check all neighbors for each number in the matrix and sum...
How can I extract part of a PChar into a string?
string,delphi,optimization,pchar
Let's consider the corner cases. I think they are: AInput invalid. AStart < 1. AStart > FLength. ASubstringLength < 0. ASubstringLength + (AStart-1) > FLength. We can ignore case 1 in my opinion. The onus should be on the caller to provide a valid PChar. Indeed your check that AInput...
Add a python flag cx_freeze to executable
python,optimization,distribution,cx-freeze,pyglet
You can use the same -O flag when you run cx_freeze to generate your final build, meaning that the cx_freeze generated bytecode will already be optimized. From the cxfreeze docs: cxfreeze hello.py --target-dir dist Further customization can be done using the following options: ... -O optimize generated bytecode as per...
Loop unrolling in inlined functions in C
Well, obviously the compiler isn't 'smart' enough to propagate the n constant and unroll the for loop. Actually it plays it safe since arg->n can change between instantiation and usage. In order to have consistent performance across compiler generations and squeeze the maximum out of your code, do the unrolling...
Compiling SCIP: 'spxsolver.h' file not found
The problem was that I was installing the scip-3.1.1.tgz rather than scipoptsuite-3.1.1.tgz. Running make on scipoptsuite-3.1.1.tgz runs perfectly fine.
Placing Limits on Optim
r,optimization,regression,rscript
This seems to work fine: opt1 <- optim(startparam, fn=ls,method="L-BFGS-B", Val=Val,Hi=Hi,Di=Di, lower =c(20,10,0), upper =c(100,70,25)) note that the values of Val, Hi, Di get passed through optim to the objective function....
Optimizing Ansible Transport\SSH for Unconventional Networks
networking,optimization,ssh,ansible
If you are working in a network where the connection might be lost 'during' execution of a play/task then I'm not sure if (read: I don't think) ansible saves the context of execution so often as to recover from such issues. If your network is bad, you should fix that....
Brent's method in the R optim implementation always returns the same local minimum
Your function is NOT convex, therefore you will have multiple local/global minima or maxima. For your function I would run a non traditional/ derivative free global optimizer like simulated annealing or genetic algorithm and use the output as a starting point for BFGS or any other local optimizers to get...
Optimizing point - circle distance method
python,opencv,numpy,optimization,cython
Use scipy.spatial.distance.cdist for the distance calculation in points_distance. First, optimize your code in pure Python and numpy. Then if necessary port the critical parts to Cython. Since a number of functions are called repeatedly a few ~100000 times, you should get some speed up from Cython for those parts. Unless,...
Does LINQ make use of underlying data structure?
They do where it makes sense, typically not for the actual type but for an interface (for example they check for IList when it helps speedup)
make all elements in list equal with minimal cost
Determinstic variant First a more efficient but deterministic approach: occurs_most([],_,0). occurs_most(List,X,Nr) :- msort(List,[H|T]), most_sort(T,H,1,H,1,X,Nr). most_sort([Hb|T],Ha,Na,Hb,Nb,Hr,Nr) :- !, Nb1 is Nb+1, most_sort(T,Ha,Na,Hb,Nb1,Hr,Nr). most_sort([Hc|T],_,Na,Hb,Nb,Hr,Nr) :- Nb > Na, !, most_sort(T,Hb,Nb,Hc,1,Hr,Nr). most_sort([Hc|T],Ha,Na,_,_,Hr,Nr) :- most_sort(T,Ha,Na,Hc,1,Hr,Nr). most_sort([],Ha,Na,_,Nb,Ha,Na) :- Na >= Nb, !. most_sort([],_,_,Hb,Nb,Hb,Nb). First you use msort/2 to sort the list. Then you iterate over...
How can I efficiently create unique relationships in Neo4j?
If you want to create unique relationships you have 2 options: Prevent the path from being duplicated, using MERGE, just like @user2194039 suggested. I think this is the simplest, and best approach you can take. Turn your relationship into a node, and create an unique constraint on it. But it's...
Ackley optimization Matlab
Since you mentioned "evolution strategy" in your comment to @Divkar, I am assuming you want to optmize the ackley function using any evolutionary algorithm. In fact, if this is the case and if you are familiar with the Particle Swarm Optimization (PSO) , there is a submission (among many) in...