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Kaprekar numbers
Test if the input is a Kaprekar number: <http://mathworld.wolfram.com/KaprekarNumber.html>. Return a logical true or false. ...

9 years 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.wikipedi...

9 years ago

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Armstrong Number
Determine whether the given input n-digit number is Armstrong Number or not. Return True if it is an Armstrong Number. An n-D...

9 years ago

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Parasitic numbers
Test whether the first input x is an n-parasitic number: <http://en.wikipedia.org/wiki/Parasitic_number>. ( _n_ is the second in...

9 years ago

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Polygonal numbers
The task of <http://www.mathworks.co.uk/matlabcentral/cody/problems/5 Problem 5> is to calculate triangular numbers. By playing ...

9 years ago

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Polite numbers. Politeness.
A polite number is an integer that sums of two or more consecutive positive integers. Politeness of a positive integer is a num...

9 years ago

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Polite numbers. N-th polite number.
A polite number is an integer that sums of at least two consecutive positive integers. For example _7 = 3+4_ so 7 is a polite...

9 years ago

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Evil Number
Check if a given natural number is evil or not. Read more at <https://oeis.org/A001969 OEIS>.

9 years ago

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Narcissistic number ?
Inspired by Problem 2056 created by Ted. In recreational number theory, a narcissistic number is a number that is the sum of ...

9 years ago

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Find the 9's Complement
Find the 9's complement of the given number. An example of how this works is <http://electrical4u.com/9s-complement-and-10s-c...

9 years ago

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Compute Fibonacci Number
Compute the _n_-th Fibonacci Number f(0) = 0, f(1) = 1, f(2) = 1, f(3) = 2, ... f(42) = 267914296

9 years ago

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Implement simple rotation cypher
If given a letter from the set: [abc...xyz] and a shift, implement a shift cypher. Example: 'abc' with a shi...

9 years ago

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How many trades represent all the profit?
Given a list of results from trades made: [1 3 -4 2 -1 2 3] We can add them up to see this series of trades made a profit ...

9 years ago

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Find a subset that divides the vector into equal halves
Given a vector x, return the indices to elements that will sum to exactly half of the sum of all elements. Example: Inpu...

9 years ago

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Flag largest magnitude swings as they occur
You have a phenomenon that produces strictly positive or negative results. delta = [1 -3 4 2 -1 6 -2 -7]; Marching thr...

9 years ago

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Distance walked 3D
suppose you go from x-y-z coordinates [3,4,2] to [0,0,2] to [0,1,2] to [1,1,2], to [1,1,20] then you walked 25 units of distance...

9 years ago

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Flip the main diagonal of a matrix
Given a n x n matrix, M, flip its main diagonal. Example: >> M=magic(5); >> flipDiagonal(M) 9 24 1 ...

9 years ago

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Return elements unique to either input
Given two numeric inputs a and b, return a row vector that contains the numbers found in only a or only b, but not both. For ex...

9 years ago

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Determine if a Given Number is a Triangle Number
*Description:* Determine if the elements of an input array are triangle numbers and return the result as an array with the sa...

9 years ago

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Replace Vector Elements
Replace all elements in a vector which are equal to or smaller than zero with 0.1. Example: A = [1 2 3 -1 0 2 -3 -80]; ...

9 years ago

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Replicate elements in vectors
Replicate each element of a row vector (with NaN) a constant number of times. Examples : n=2, A=[1 2 3] -> [1 1 2 2 3 3] n=0...

9 years ago

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Find max
Find the maximum value of a given vector or matrix.

9 years ago

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Make a run-length companion vector
Given a vector x, return a vector r that indicates the run length of any value in x. Each element in r shows how many times the ...

9 years ago

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Back to basics 23 - Triangular matrix
Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix, return a matrix with all elements above a...

9 years ago

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All your base are belong to us
Find the base _b_ logarithm of the input decimal number _x_. Express the output as a decimal number. The first argument is the n...

9 years ago

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Rotate a Matrix by 90 degrees
Rotate a Matrix by 90 degrees Example: If the input is: X = 1 2 3 4 5 6 7 8 9 ...

9 years ago

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Add two numbers
Calculate the sum of two numbers. Example input = [2 3] output = 5

9 years ago

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Given a window, how many subsets of a vector sum positive
Given a vector: [1 0 -1 3 2 -3 1] and a window of 2, A sliding window would find: 1 + 0 = 1 0 - 1 = -1 ...

9 years ago

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How to find the position of an element in a vector without using the find function
Write a function posX=findPosition(x,y) where x is a vector and y is the number that you are searching for. Examples: fin...

9 years ago

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Reverse the vector
Reverse the vector elements. Example: Input x = [1,2,3,4,5,6,7,8,9] Output y = [9,8,7,6,5,4,3,2,1]

9 years ago