Good update frequency | Web Hosting Talk

Hi friends,

I have a server with 200-250 clients and cannot reboot server every day (because her webs will be down).

I contacted with CloudLinux support and they told me:

-All her software are updated with “yum update”: CloudLinux, Imunify360, Kernelcare, etc.
-Only need reboot server when update the Kernel, not when update other CloudLinux things (but with Kernelcare i can wait time because patch are applied in RAM).

I need know:

-What frequency you recommend me reboot the server?, ¿each 15 days, each month…?
-Anybody know if WHM/cPanel, LiteSpeed, Softaculous and JetBackup also updated when system use “yum update”?.

If in your experience recommend me other update method for servers please tell me.

Thank you very much.

programming challenge – Sort Characters By Frequency Java

For context, I worked on the LeetCode May 2020 Challenge Week 3 Day 1. The challenge was described as this:

Given a string, sort it in decreasing order based on the frequency of

Example 1:

Input: "tree"

Output: "eert"

Explanation: 'e' appears twice while 'r' and 't' both appear once. So
'e' must appear before both 'r' and 't'. Therefore "eetr" is also a
valid answer.

Example 2:

Input: "cccaaa"

Output: "cccaaa"

Explanation: Both 'c' and 'a' appear three times, so "aaaccc" is also
a valid answer. Note that "cacaca" is incorrect, as the same
characters must be together.

Example 3:

Input: "Aabb"

Output: "bbAa"

Explanation: "bbaA" is also a valid answer, but "Aabb" is incorrect.
Note that 'A' and 'a' are treated as two different characters.

Anyways, I looked up some popular solutions. One was to get the frequency of each character and sort, and the other was the use a heap. I liked both of these solutions, but I wanted to make one where there was no sorting.

My solution involved an idea of an ArrayList of “tiers,” where the index of the tier represents the frequency. Each tier consists of an ArrayList containing the characters which the corresponding frequency. As letters increase in frequency, the higher frequency tier they move up. I also used a HashMap to keep track of which frequency tier each character was in. Upon finishing iterating through the whole string, I simply use a StringBuilder to append the letters starting at the bottom tier, reverse the StringBuilder, then return the String. I was hoping someone could give me pointers (ha, code pun) on optimizing/modifying this approach without including any kind of sorting. Below is the functional code:

public static String frequencySort(String s) {
        if (s.length() <= 1) return s;

        ArrayList<ArrayList<Character>> tieredFreq = new ArrayList<>(); // stores characters at their proper frequency "tier"
        HashMap<Character, Integer> tierOfChars = new HashMap<>(); // maps the characters to their current frequency tier
        tieredFreq.add(null); // tier 0

        for (char c : s.toCharArray()) {
            tierOfChars.put(c, tierOfChars.getOrDefault(c, 0) + 1); // add char or increment the tier of the character
            int i = tierOfChars.get(c); // i = tier of the character
            if (tieredFreq.size() <= i) tieredFreq.add(new ArrayList<>()); // if not enough tiers, add a new tier
            if (i > 1) tieredFreq.get(i - 1).remove(new Character(c)); // if c exists in previous tier, remove it
            tieredFreq.get(i).add(c); // add to new tier

        StringBuilder result = new StringBuilder();
        for (int i = 1; i < tieredFreq.size(); i++) { // iterate through tiers
            ArrayList<Character> tier = tieredFreq.get(i); // get tier
            for (Character c : tier) { // for each char in tier, append to string a number of times equal to the tier
                for (int j = 0; j < i; j++) result.append(c);

        result.reverse(); // reverse, since result is currently in ascending order
        return result.toString();

How to display the frequency spectrum of android audio output for both channels?

I want to stream DLNA audio signal to my android device and display the audio frequency spectrum for both stereo channels.

There are some apps that accept the DLNA stream on android, no problem there.
What I couldn’t find is an app that would also have built-in visualizer with a spectrum analyzer preset.

I could use a separate spectrum analyzer app, there are many to choose from. But most of them only display the spectrum of the sound coming from the microphone, not from what is currently playing on android.

The closest alternative I have found is projectM, but just couldn’t find a preset for it that would simply display the spectrum of both channels, without any other effects.

So, if we could display something like this for currently playing audio on android, it would be perfect. This may look like a single channel audio, but the blue bars represent the left channel, red – right, and purple is the sound that is coming from both channels):

enter image description here

Server backup frequency


I want to configure 2 backups every day: with default WHM/cPanel and with JetBackup. I need know if you recommend me do this or is re… | Read the rest of

I want to convert a piece of violin that I heard on YouTube into a waveform (amplitude as a function of time or frequency)

I want to convert a piece of violin that I heard on YouTube into a waveform (amplitude as a function of time or frequency). How to do this with Mathematica, please? I suspect it may have something to do with processing a MIDI file. That’s all I know.

filtering – Try to filter components at zero frequency with a low pass filter

seq = Rescale[
Table[SawtoothWave[n/16.], {n, 0, 255}] + 
RandomReal[{-0.1, 0.1}, 256]];
GraphicsRow[{Periodogram[seq, PlotRange -> All], 

GraphicsRow[ListLinePlot /@ {seq, LowpassFilter[seq, .5]}] Spectrogram[seq, 128, 32]}]

My understanding is that I am running seq through a low pass filter [.5]

Frequency of exchanges is critical

The frequency of transactions represents a profit opportunity. The more opportunities we can find, the more profit we should expect. For example, a strategy that has a very high profit factor of 4 (the profit factor is total profits divided by total losses) may not produce as much profit as a more active system that has a factor of profit of only 2. Since the strategy with the lower profit factor is profitable and it has much more possibilities than it can easily produce more total profit than the system with the much higher profit factor.

gimp – Remove the low frequency background

I have a series of images that are vignetted – an artifact that I want to reduce from the images (see the smoothed and undersampled image). enter description of image here

My approach is to subtract a highly smoothed version of the actual image to remove the non-homogeneous background brightness, but the results were far from satisfactory.
Changing the black point of the image obviously doesn't work either.

Is there a way I miss to deal with such a problem?

Information about the lens vignetting behavior is not available beyond what I see in the pictures.

One approach I can imagine for working is to subtract a frequency filtered version of the image where I only retain the very low radial-symmetrical frequencies of the original, thus keeping the high frequency content of the stars intact. and galaxies. Still, I can't seem to find a way to do it safely than writing such a plugin myself. Am I missing an approach with gimp (or another program I can work on under Linux)?

usability – Best way to display frequency

Do you know of another way to represent a list of items that have their own frequency options (weekly, monthly, daily) from which you can choose.
I was thinking maybe create like an array and add 3 checkboxes under each option or create something similar to segmented control. Example

I was also thinking of adding a drop-down list where you can choose between these three options.
What do you think is the best option for me?

differential equations – How to solve the natural frequency of the cantilever beam by mathematical method

I want to calculate the natural frequency of the cantilever beam according to the theoretical method.

enter description of image here

I find an article on how to solve the free vibration frequency of a cantilever beam with the finite element method.

ps = {Inactive(
      Div)({{0, -((Y*ν)/(1 - ν^2))}, {-(Y*(1 - ν))/(2*(1 
- ν^2)), 0}}.Inactive(Grad)(v(x, y), {x, y}), {x, y}) + 
      Div)({{-(Y/(1 - ν^2)), 
        0}, {0, -(Y*(1 - ν))/(2*(1 - ν^2))}}.Inactive(Grad)(
       u(x, y), {x, y}), {x, y}), 
      Div)({{0, -(Y*(1 - ν))/(2*(1 - ν^2))}, {-((Y*ν)/(1 
- ν^2)), 0}}.Inactive(Grad)(u(x, y), {x, y}), {x, y}) + 
      Div)({{-(Y*(1 - ν))/(2*(1 - ν^2)), 
        0}, {0, -(Y/(1 - ν^2))}}.Inactive(Grad)(
       v(x, y), {x, y}), {x, y})} /. {Y -> 10^3, ν -> 33/100}

{vals, funs} = 
 NDEigensystem({ps}, {u, v}, {x, y} ∈ 
   Rectangle({0, 0}, {5, 0.25}), 8)
theory = {0, 0, 0, 22/L^2 Sqrt((Y d^2)/(12 1)), 
   61.7/L^2 Sqrt((Y d^2)/(12 1)), 121/L^2 Sqrt((Y d^2)/(12 1)), 
   200/L^2 Sqrt((Y d^2)/(12 1)), π/L Sqrt(Y/1.)} /. {Y -> 10^3, 
   d -> 0.25, L -> 5}
TableForm(Transpose({Sqrt(Abs(vals)), theory}), 
 TableHeadings -> {Automatic, {"Calculated", "Theory"}})
bcs = DirichletCondition({u(x, y) == 0, v(x, y) == 0}, x == 0);

{vals, funs} = 
  NDEigensystem({ps, bcs}, {u, v}, {x, y} ∈ 
    Rectangle({0, 0}, {5, 0.25}), 5);
theory = {3.52 Sqrt((Y d^2)/(12 L^4)), 22 Sqrt((Y d^2)/(12 L^4)), 
    61.7 Sqrt((Y d^2)/(12 L^4)), π/2 Sqrt(Y/L^2), 
    121 Sqrt((Y d^2)/(12 L^4))} /. {Y -> 10^3, d -> 0.25, L -> 5.};
TableForm(Transpose({Sqrt(Abs(vals)), theory}), 
 TableHeadings -> {Automatic, {"Calculated", "Theory"}})
mesh = funs((1, 1))("ElementMesh");
Column(Table(uif = funs((n, 1));
  vif = funs((n, 2));
  dmesh = 
   ElementMeshDeformation(mesh, {uif, vif}, "ScalingFactor" -> 0.1);
      "ElementMeshDirective" -> 
       Directive(EdgeForm(Red), FaceForm())))}), {n, 5}))

But I would like to know how to solve the natural frequency of the model in the post above according to the method of solving the partial differential equation.

enter description of image here

Other related links:

How do you find the eigenvalues ​​of a PDE (Dynamic Euler-Bernoulli beam)?

Inhomogeneous dynamic Euler-Bernoulli beam equation with discontinuous parameters

Analytical solution of the dynamic equation of the Euler-Bernoulli beam with compatibility condition