Anh Thu

Last seen: 10 months ago | Active since 2024

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String Array Basics, Part 1: Convert Cell Array to String Array; No Missing Values
<http://www.mathworks.com/help/matlab/characters-and-strings.html String array> and cell array are two types of containers for s...

10 months ago

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Sum of series V
What is the sum of the following sequence: Σk(k+1) for k=1...n for different n?

11 months ago

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Sum of series IV
What is the sum of the following sequence: Σ(-1)^(k+1) (2k-1)^2 for k=1...n for different n?

11 months ago

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Sum of series III
What is the sum of the following sequence: Σ(2k-1)^3 for k=1...n for different n?

11 months ago

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Sum of series II
What is the sum of the following sequence: Σ(2k-1)^2 for k=1...n for different n?

11 months ago

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Sum of series I
What is the sum of the following sequence: Σ(2k-1) for k=1...n for different n?

11 months ago

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Right Triangle Side Lengths (Inspired by Project Euler Problem 39)
If p is the perimeter of a right angle triangle with integral length sides, { a, b, c }, there are exactly three solutions for p...

11 months ago

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Determine whether a vector is monotonically increasing
Return true if the elements of the input vector increase monotonically (i.e. each element is larger than the previous). Return f...

11 months ago

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Finding peaks
Find the peak values in the signal. The peak value is defined as the local maxima. For example, x= [1 12 3 2 7 0 3 1 19 7]; ...

11 months ago

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Television Screen Dimensions
Given a width to height ratio of a TV screen given as _w_ and _h_ as well as the diagonal length of the television _l_, return t...

11 months ago

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Mersenne Primes vs. All Primes
A Mersenne prime (M) is a prime number of the form M = 2^p - 1, where p is another prime number. <https://www.mathworks.com/matl...

11 months ago

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The Goldbach Conjecture
The Goldbach conjecture asserts that every even integer greater than 2 can be expressed as the sum of two primes. Given the eve...

11 months ago

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Pi Digit Probability
Assume that the next digit of pi constant is determined by the historical digit distribution. What is the probability of next di...

11 months ago

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Find the next prime number
Find the next prime number or numbers for given n. For example: n = 1; out = 2; or n = [5 7]; out = [7 11]; ...

11 months ago

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Make a vector of prime numbers
Input(n) - length of vector with prime numbers Output(v) - vector of prime numbers Example: * n=1; v=2 * n=3; v=[2 3 5...

11 months ago

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Largest Twin Primes
<http://en.wikipedia.org/wiki/Twin_prime Twin primes> are primes p1, p2 = p1 + 2 such that both p1 and p2 are prime numbers. Giv...

11 months ago

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Mersenne Primes
A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

11 months ago

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Find nearest prime number less than input number
Find nearest prime number less than input number. For example: if the input number is 125, then the nearest prime number whi...

11 months ago

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Sophie Germain prime
In number theory, a prime number p is a *Sophie Germain prime* if 2p + 1 is also prime. For example, 23 is a Sophie Germain prim...

11 months ago

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Factorize THIS, buddy
List the prime factors for the input number, in decreasing order. List each factor only once, even if the factorization includes...

11 months ago

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Get all prime factors
List the prime factors for the input number, in decreasing order. List each factor. If the prime factor occurs twice, list it as...

11 months ago

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Numbers with prime factors 2, 3 and 5.
Make a function which takes one positive integer n and returns a matrix with the numbers of the form (2^i)*(3^j)*(5^k) which are...

11 months ago

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Proper Factors
Generate the proper factors of input integer x and return them in ascending order. For more information on proper factors, refer...

11 months ago

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Multiples of a Number in a Given Range
Given an integer factor _f_ and a range defined by _xlow_ and _xhigh_ inclusive, return a vector of the multiples of _f_ that fa...

11 months ago

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Smith numbers
Return true if the input is a Smith number in base ten. Otherwise, return false. Read about Smith numbers at http://en.wikipedia...

11 months ago

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Prime factor digits
Consider the following number system. Calculate the prime factorization for each number n, then represent the prime factors in a...

11 months ago

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Project Euler: Problem 8, Find largest product in a large string of numbers
Find the greatest product of five consecutive digits in an n-digit number. 73167176531330624919225119674426574742355349194934...

11 months ago

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Project Euler: Problem 10, Sum of Primes
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below the input, N. Thank you <http:/...

11 months ago

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Project Euler: Problem 9, Pythagorean numbers
A Pythagorean triplet is a set of three natural numbers, a b c, for which, a^2 + b^2 = c^2 For example, 3^2 + 4^2 = 9 + 16 ...

11 months ago

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Project Euler: Problem 7, Nth prime
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the Nth prime numb...

11 months ago