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Mastering Development

How to compare elements within a list of case classes?

I have case class Person Person(id: String, birthdate: Int, movedate: Int ) And a list of these case classes called personRegistry personRegistry(Person(A1, 1, 5), Person(A2, 22, 30), Person(A3, 4, 20), ……) How do I find whether any of the Person’s have their birthdate / movedate fall within other Persons’ birthdate and movedate, and then group […]

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User Help

GRUB Bootloader with root LUKS encryption: Only grub shell

I would appreciate help and hints to solve a problem with the GRUB bootloader. I have a system with root LUKS encryption. Means that except the partition with the bootloader, the whole system is in an encrypted LUKS container. I am unsure where the possible problems are, so I tell you some more details. After […]

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Mastering Development

Flask Application with multiprocessing randomly connection refused with multi request

I have an API written in a flask that crawls data from the site using selenium. when making a single request it works fine. but, when I make multiple requests from my local then gives connection refused error for some requests. app.py app = Flask(__name__) if __name__ == ‘__main__’: app.run(host=”0.0.0.0″, port=5001, debug=False) when I make […]

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Ask Mathematics

How to obtain vertices for tetrahedron defined by points?

I’m implementing the formula from https://math.stackexchange.com/a/2841311 but this formula talks about vertices. Given 4 points $p1,p2,p3,p4$, how do I find the vertices of my tetrahedron? I did $v1 = p2-p1\\v2 = p3-p2\\v3 = p4-p3$ then $V = \frac{1}{6}|(v1\cdot v2) \times v3|$ but I’m getting lots of 0 values from this formula, and some other strange […]

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Ask Mathematics

Markov models and calculating the period of each state

I am currently studying Markov models from the textbook Introduction to Modeling and Analysis of Stochastic Systems, second edition, by Kulkarni. I have just encountered the concept of periodicity in chapter 2: Definition 2.4. (Periodicity). Let $\{ X_n, n \ge 0 \}$ be an irreducible DTMC on state space $S = \{1, 2, \dots, N […]

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The coordinates of the point T such that PT, QR are parallel and PR, QT are orthogonal

P(3,-1,3) Q(0,7,-2),R(-9,3,-3) and S (6,3,2) be four points in R3 Find the coordinates of the point T such that PT, QR are parallel and PR, QT are orthogonal *I have no idea how to do please help me

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Mastering Development

How to merge two versioned tables?

There are two tables: Table1(id, p1, p2, date_from, date_to): (1, ‘z’, 55, ‘01.05.2010 12:30:20’, ‘17.05.2010 13:10:14’), (1, ‘c’, null, ‘17.05.2010 13:10:15’, ‘18.01.2010 04:13:15’), (1, ‘c’, 25, ‘18.01.2010 04:13:16’, ‘01.01.9999 00:00:00’); Table2(id, p3, date_from, date_to): (1, 15, ‘01.04.2010 12:30:20’, ‘02.05.2010 13:10:14’), (1, 35, ‘02.05.2010 13:10:15’, ‘01.01.9999 00:00:00’); It is necessary that when merging 2 tables, there […]

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Development

LNK2001 Unresolved external symbol “public: virtual void …” in C++ Interface class

I have tried using pure virtual methods along with testing others answers on similar issues, but everything has continued to result in the same problem. So I have this class Shape that acts as an interface declaring the virtual void Draw() method. This function is later overridden in three other classes for primitive shapes, and […]

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Development

Time difference in execution of MySQL joins

I had a queries in which there was left joins were used and it was taking 30 seconds to complete the execution and return the dataset on mysql terminal. But when I have changed it to join its execution time has been reduced significantly from 30 to 12 seconds. I know this is too much […]

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Development

Why do I get different renditions of the same code in Matlab and Octave (and within Matlab)?

For context, this is the original post that motivated this question. Here is the code (please note that I am included the code as is, although the plots are generated by x-ing out of the graphics window when the simulation starts running, and letting the program open automatically new windows without the surface): x = […]