# Tag Info

### How to prove that a system is real-time?

It depends on your definition of "real-time system". A standard definition is: a system is real-time if it will respond within $T$ seconds, with probability at least $P$. Here you need to fill in ...
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### What does it mean that HDLs "explicitly include the notion of time"?

Programming languages usually don't have a notion of time. They describe how things are sequenced, but usually they don't go further. When they do, that's relegated to the library part of the ...
• 3,069
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### Why computer didn't use cesium atom to define 1 second?

First of all, the reason personal computers dont't use atomic clocks based on caesium is price. One CSAC (chip scale atomic clock) costs 5000 USD nowadays. The added precision is not worth the price ...
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### What guarantees do "soft" real-time operating systems actually provide

To define "soft real-time," it is easiest to compare it with "hard real-time." Speaking casually, most people implicitly have an informal mental model that considers information or an event as being "...
Accepted

### If current time in milliseconds is considered good enough random seed for a pseudorandom number generator, why not just use that time directly?

The key property that we want from (non-cryptographic) pseudorandom numbers is that they "look" independent. In particular, say you have some algorithm that requires a PRNG to perform well and you ...

### If current time in milliseconds is considered good enough random seed for a pseudorandom number generator, why not just use that time directly?

It's not random. It increases by 1 every milliseconds. In computer terms, it stays unchanged for a loooooong time (millions of clock cycles). But current system time in milliseconds is most ...
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### How to prove that a system is real-time?

You need to provide a more precise description of your system and real-time requirements. If you are interested in only the timeliness and timeliness predictability of the response to the first event,...

### What is 'real time' in a Computer Vision context?

In computer science, a real-time computing (RTC) system is one that guarantees a response before a previously set deadline. For a stream of images, that implies that a real-time system is one that ...
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### What is 'real time' in a Computer Vision context?

There is no one answer to this question. "Real time" can mean very different things, depending on what kind of sensor or sensors you are using, and what you are trying to do. By the way, editing and ...
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### Are there any efficient algorithems to find packets similarities in a list?

There are many possible approaches for measuring document similarity: edit distance shingling Jaccard similarity TF-IDF and cosine similarity https://stackoverflow.com/q/101569/781723 https://...
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### What does it mean that HDLs "explicitly include the notion of time"?

Imperative languages only implicitly have a notion of time. Primarily, demarcated by mutation of state, i.e. there's a before some variable was mutated and an after some variable was mutated. ...
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### timed automata - advance only in certain states

So, after looking deeper into the subject I found the solution. Posting in case somebody else needs an answer and is unfamiliar with the subject. What I was looking for is called a Stopwatch ...
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### Missing 770201 seconds in Y2K2038

I think you have an error in your math. 19 January 2038 at 03:14:07 UTC is $t_1 = 2147483647$ seconds after the epoch. 13 December 1901 at 20:45:52 is $t_2 = 2147483648$ seconds before the epoch. ...
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### UTC Time Offset

The timestamp you are seeing is the time in the given timezone using the given offset from UTC. The specific format of the timestamp you are looking at is an RFC2822 formatted timestamp which means ...
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### Which overhead is smaller - function call or passing variables between processes?

callback-based approach requires you to call a callback function every time you receive a new data packet; this is not a good approach for high-load and high-throughput network servers Who claims ...
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### Real-time systems and real-time operating systems

A system is several things working together. A real time system might include computer hardware and software. Depending on where you draw the line it might include sensors and actuators reaching into ...
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1 vote

### Wrapping the complexities of alternative algorithms: What is the proper "term" for it?

Hybrid algorithms. In sorting algorithms it's rather common, Start with quicksort and if the size of the array is small enough switch to insertion sort (much faster for small $n$). Additionally when ...
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1 vote

### Rate Monotonic maximum execution time

First of all, this problem is (weakly) NP-hard, see this paper by Ekberg and Yi, because it generalizes the problem of deciding which task sets are schedulable by Rate Monotonic. However, assuming ...
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1 vote

You can't generate a deadline from nothing. That doesn't make sense. Some tasks must be completed by a certain time, or they are useless. Only the programmer who writes the task knows whether this ...
• 159k
1 vote

### What does it mean that HDLs "explicitly include the notion of time"?

HDL's incorporate a notion of time in the following sense: they may allow you to talk about the current value of the circuit's state (e.g., registers) and the next value of its state. So, you might ...
• 159k
1 vote

### Real time application with DFA or NFA application

A real time application is one in which some computation needs to be done very fast, always. For example, controlling an airplane, decoding an MPEG, and Skype are real time applications. Web browsing ...
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### Real time application with DFA or NFA application

DFA/NFA in a real time application ? consider designing a parser for user inputs where each input is a word w="http://some-address.com?key[1]=value1&key[2]=value2..." consider having each key[i] ...

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