C++ :: Analysis Of Discrete Wavelet Transform - Modifying For Loop To Make It Faster
Aug 25, 2014
I have this code which performs the analysis part of discrete wavelet transform. It works pretty well. However, I wish to reduce the time that it consumes even further. I did use reserve() and it worked upto few msec.
int rows = signal.size();
int cols = signal[0].size();
int cols_lp1 =(int) ceil( (double) cols / 2);
vector<vector<double> > lp_dn1(rows, vector<double>(cols_lp1));
vector<double> temp_row;
temp_row.reserve(512);
[Code] ....
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Dec 9, 2014
I'm trying to optimize this code using openMP. The line I added made it run about twice as fast but I'm trying to figure out how to make it even faster. Could reshaping the loops potentially increase the speed?
//4 threads
int listsize=15000;
#pragma omp parallel for shared(f) private(i,j,hash)
for(i = 0; i < listsize; i++) {
printf("Thread: %d i: %zu wl_size: %zu
",omp_get_thread_num(),i,wl_size);
for (j = 0; j < num; j++) {
h = f[j] (getw(list, i));
c[h] = 1;
} }
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Jan 30, 2014
I have a 125X125 array, each element is 55 bits. The cache line for the CPU ( Cortex A9) is 32 bits. Is there anyway to do optimizations, like loop tiling that would make multiplication and calculations faster?
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Jul 10, 2014
I am trying to modify a user control while modifying the main form. For example i have my main form open in one visual c# window and my user controls in another. However it seems that in order for my code changes in my user control to have any effect on the main form i need to close all my c# windows and then re-open them and even then that sometimes doesn't work am i doing anything wrong or is this supposed to happen??
Also yes i am saving and clicking build solution on my user controls.
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Mar 9, 2015
I'm trying to program an arduino to generate a Trapezoidal Motion Profile to control a DC motor with a quadrature encoder.
Essentially, the user will input the desired Target Position, Max Velocity and Acceleration (decel = -accel) and the code will calculate the target position versus time which will then be compared with the actual position. The result will then be subject to a PID calculation
My initial assumption was that I could use basic Newtonian physics to determine position (i.e. PT = P0 + V0T + 1/2AT2, VT = V0 + AT). However, after reading through documentation for pre-existing motion controllers, I discovered that the prevalent method was to use a discrete time method, which is as follows:
VK = VK-1 + A (A = Acceleration)
PK = PK-1 + VK-1 + A/2
I'm having a hard time understanding quite how this equation would generate the target position versus time. In the case of Velocity, it seems to just add the acceleration to the current velocity. But what about everything in between?
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Oct 19, 2014
Can I possibly get a better implementation of a prime number detecting algorithm than the one I already have below?
Code:
#include <cstdio>
#include <cstdlib>
int main() {
int no, high, low;
int divisor;
[Code] .....
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Nov 20, 2014
I'm trying to write a program for a lab, I know how easy it is but cant see to crack it.
I need to make a program using while or for loop.
I must have the user type a number, for an input value an output value but then do it again several times but without it going on forever asking again and again.
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Aug 29, 2014
How to make a loop so program never end, it end only by typing "EXIT"
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Mar 25, 2015
#include <iostream>
#include <vector>
#include <list>
[Code].....
The problem is it's not finding the shortest path.
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Oct 26, 2013
I need to do make a loop inside a condition. Can it be done? I don't want to call another function to do it. Any way at all without calling separate function inside the if? I just want to do:
if (
for (int i = 0; i<=10; i++)
{
//stuff related to the for loop
} )
{
//stuff related to the initial if condition
};
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Feb 11, 2014
I am looking to write a program that, given a particular word, looks at a plain text document and gives a list of words that appear within x words of the given word along with a count of how many times it appears.
Do I need to use regex to do the pattern matching here? Is there a particular data structure that I should use that is particularly suited to a task like this? I don't want to reinvent the wheel, it seems like there should be libraries that would already do this sort of thing but searches have turned up nothing.
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Mar 25, 2015
Undirected graph G = {V, E} is given by the list next to the DS. Let u, v of V. Construction of two paths algorithm A1 (u, v) and A2 (u, v) such that no edge in common and have the shortest total length.
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Nov 15, 2013
I have an exam in C programming I'm a little stuck on loops..I have to make a program that multiplies the loop variable by 2 then takes away 1... easy, that was a for loop no problem
for (x=3; x<=65; x=x*2-1)
that should print out 3 5 9 17 33 65 however, my lecturer has given the task for it to reverse, but not to display the number 17 on the way back down using an if statement...however, this time it must be a do while loop... This is what I have so far.
Code:
#include <stdio.h>
#include <stdlib.h>
int main()
{
int x = 129;
}
[code]....
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Apr 4, 2013
I'm making a program for a MMO I play. It calculates the cash and resources needed to build certain 'modules'. I'm having trouble to do something very simple : make a loop until the user asks to break the loop. Here is what the interface looks like :
What module do you want to install?
(Examples: 'Avenger' or 'VLLT')
dd // I input this
DD. COST each : 60,000 cr.
How many do you want? (Modules left:15)
(NOTE : You may enter a negative number if you made a mistake)
3 // I input this
Current Total Module Price : 180000 cr
+6 droids
[Code] ....
The bigger code box below is a part of the code I made. What I deleted is uninteresting, it's just the same thing again : other resources, other 'modules'...
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
struct resources// Defines the amount of resources and their price
[Code] ....
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Dec 11, 2013
Something that does something like this
at this point run a loop for all players, in this loop use random to determine the face and depending on the face run a loop (for roll again etc) or give next user the chance.
And this loop is 2-12 people, all rolling die.
They draw 3 die out of a cup of 12.
Then they roll the 3 die, getting fish, hook, or boot on each die.
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Dec 11, 2013
[URL] ....
This is my code, but how can I implement this?
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Oct 30, 2013
I have the problem of trying to find the smallest natural number that makes two consecutive terms in single precision floating point notation in the riemann zeta function equal. So basically the riemann function of 2 is given by:
sum of 1/(k^2) from k=1 until infinity, so : 1/(1^2) + 1/(2^2) + 1/(3^2) + ...... until infinity.
Now the question asks to stop at the smallest natural number n, at which the sum 1/1^2 + 1/2^2 + ......+ 1/(n^2) is equal to the sum 1/1^2 + 1/2^2 + ..... + 1/((n+1)^2) in single precision floating point notation.
Now well the obvious way to look for n would be on this way:
float i = 1.0;
float n = 1/(i);
float n1 = 1/(i+1.0);
while ( n != n1){
i += 1.0;
n = 1/i;
n1 = 1/(i+1.0);}
But first of all this is obviously completely inefficient and I dont think it will yield a valid answer for any float variable, i.e. I dont think the sum until 1/n^2 and 1/(n+1)^2 will ever differ. I tried it out with the largest possible value of a variable of type float and the values were still seen as unequal in C++. How to do this? Will C++ find a value for n for which the condition holds? Is the compiler or my hardware important for this, i.e. would I get different results on a different pc?
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Mar 29, 2014
I am creating a reaction game using a series of lasers and LRDs and need to make a function which waits for a specific pin in portb to be triggered high before it can move onto waiting for the next pin to be triggered. The time lasped before the "game loses" needs to get exponentially faster as the game goes on.
I am using statements such as if(input(PIN_B0)==1 generate_tone(G_note[2], 1000); but unsure how to write in c "wait x amount of time, if trigger move onto next random pin or no trigger go to lose function.
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Feb 15, 2015
is it better to reuse an existing variable or create a new variable for the following situation:
/* Is this faster: */
glm::mat4 newViewModelMatrix = (*existingViewMatrix) * (*existingModelMatrix);
/* Or is this faster? */
glm::mat4 existingViewModelMatrix; /* declared in class header - initial value assigned in class constructor */
existingViewModelMatrix = (*existingViewMatrix) * (*existingModelMatrix);
Just wondering if it makes a difference or not.
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Dec 31, 2013
I'm working on a code that needs to loop a switch case back to the beginning after a certain input is entered.
ex) Code:
printf("Select an option);
printf("1. Play game");
printf("2. Status");
printf("3. Exit");
scanf("%i", &userinput);
switch(userinput);
[Code]...
For my program, I want option 2 to display something, then loop back to "select and option" after the user presses enter. How would I write that? Would i use a while? do while?
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Nov 27, 2014
Write a program to make a table for any input number and then continuesly ask to press y to print more table and if you press any key other than y then program must be terminate using while loop and do while loop. How to start or end with it.
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Jul 31, 2014
My while loop is the problem. I want to use a non-recursive function to make the triangle number the sum of all whole numbers from 1 to N.
#include "stdafx.h"
#include <iostream>
using namespace std;
int triangle(int t);
[Code] ....
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Feb 9, 2015
I have to make a function that i'll later be able to use for a ceasar cypher. The letters should shift a user inputted number. This is what I have so far:
char shiftChar(char c, int s) {
char ch = c;
int shift = s;
int newC;
newC = int(ch) + shift;
return newC;
}
The problem with this, is that it doesn't loop back to the start of the alphabet once i get past z.
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Mar 4, 2013
I have a text file which consists of 907 objects and 1000 feature vector for each object. Is there any Library (Eigen/Boost) to calculate Principle Component Analysis(PCA)?
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Feb 16, 2014
I am working on my second c++ project that is a statistical analysis of a vector data set of integers. I created a struct called range with a maximum value, minimum value and count for occurrence. The frequencies are stored in a vector<range>.
I have tried messing around with the increment to get the high range test above the maximum element, though my ranges cumulatively increase by 9.9. I'm not sure how the professor's program has the distance between high and low ranges as 10 instead of 9.9, which is the increment. I'm also unsure why half way through his buckets, the ranges appear as 9.99 briefly and then return to 10 after (40.00 - 49.99 then 49.99 - 59.99). I feel like I am missing something very obvious on line 04 or 10 in my code.
Here is the code for the frequency that accepts a vector reference for my data set of integers.
void frequency(vector<int>& data_set){
double max = findMax(data_set);
double min = findMin(data_set);
double increment = (max - min) / 10;
double percentage = 0.0;
[Code] ....
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Apr 14, 2015
This is how my .xml page looks in a web browser. Is there a way to transform my .xml file into .txt file so that the text file would look like this?
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