結果:

Kilsu Kim
最後のアクティビティ: 2023 年 10 月 19 日

Just for Fun and Curiosity: Guess the MATLAB Compile Threshold on Windows

Recently, I came across a post about the JIT compiler on this Korean blog. In the post. The writer discussed the concept of the "Compile Threshold" and how it is calculated.

"The JVM accumulates the number of calls for each method called and compiles when the number exceeds a certain number. In other words, there is a standard for checking how often it is called and then deciding, 'It is time to compile.' This standard is called the compilation threshold. But what is this and why should it be used as a standard?"

The concept of the "Compile Threshold," as used above, seems to be more commonly associated with Tracing just-in-time compilation.

The writer used the simple Java code below to calculate the threshold.

for (int i = 0; i < 500; ++i) {
  long startTime = System.nanoTime();
  for (int j = 0; j < 1000; ++j) {
 	new Object();
  }
  long endTime = System.nanoTime();
  System.out.printf("%d\t%d\n", i, endTime - startTime);
}

Since the MATLAB execution engine uses JIT compilation, I just wanted to perform the same experiment that the writer did.

I experimented using simple codes based on the code in the blog. I iterated a function 500 time using for-loop and calculated the execution time for each iteration using tic and toc. Then I plotted the execution time for each loop as blow. First five execution times are much higher than followings (10 times!) The test is very rough so I am not sure that I can conclude "MATLAB has Compile Threshold and it is 5!" but this value is actually correct ;-)

t0 = 0;
tfinal = 10;
y0 = [20;20];
timeToRun = zeros(500,1);
for i = 1:500
    tStart = tic;
    [preypeaks,predatorpeaks] = solvelotka(t0, tfinal, y0);
    tEnd = toc(tStart);
    timeToRun(i) = tEnd;
end

General

Toshiaki Takeuchi
最後のアクティビティ: 2023 年 10 月 23 日

Do you use VS Code for writing MATLAB Code?

VS Code Extension for MATLAB was introduced back in April and has been downloaded 75K times since. Do people here use VS Code for writing MATLAB code?

ThingSpeak

Adrian
最後のアクティビティ: 2023 年 10 月 26 日

Losing connection with Thingspeak after exactly 1 hour

Hi, I'm losing comms with thingspeak after exactly one hour. I'm on the free plan while I evaluate TS.

I am sending data once a minute. It works fine for one hour, and I get 200-OK responses. After exactly 1 hour, the response from TS is a 404-not found. I do a new DNS lookup, and get a new IP address for TS. Still no response. I do more DNS lookups, and get another different IP address. It cycles through 3 different IP addresses, but noe of them work one hour after bootup on my device.

I'm running an Arduino Nano with an Ethercard and the JNH library. I can still ping the arduino, serve webpages and ping a monitored device, and get NTP time, all in a 1 minute loop, so I doubt the TCP/IP stack has crashed.

after I restart the device, it works again for exactly one hour, and the I lose comms with Thingspeak again.

Any help would be appreciated!

Thanks,

Adrian

ThingSpeak

Jitse Schaafsma
最後のアクティビティ: 2024 年 4 月 4 日

MQTT.tool no connection to MQTT server

In my struggle to get my SIM7600 connected to thingspeak using MQTT, i went to the basics: simple testing of my connection:

I use this site : https://testclient-cloud.mqtt.cool

Protocol :tcp

Host : mqtt3.thingspeak.com

Port : 1883

Username : got it from my device (double checked !)

Password : got it from my device (double checked !)

When i try to connect I get the message Connection refused : bad user name or password.

I am completely lost. What basic stupi mistake am i missing. I thoroughly read the MQTT help pages.

Any help is appreciated.

Update :

When i select Dedicated connection and i also fill in the will message and will topic, i am able to update my channel. At least some progress.

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結果: