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Index of a Rational number
The set of real numbers are infinite. They are so many that real numbers can't even be enumerated. However, unlike real numbers ...

10 months ago

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Three...is a magic number.
Yes it is... It's a magic number... To help you get rid of that earworm, here's a new Cody problem. You are given a squar...

10 months ago

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Max Change in Consecutive Elements
If an array is given as input then find the index of consecutive elements that represent maximum change. Example: Input ...

10 months ago

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swap sign sum & multiply castles
It is an easy problem, if you know the answer. Given a square matrix of NxN ordinary numbers. Initially place N identical indi...

10 months ago

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Check Bertrand-Chebyshev's theorem about prime numbers
Historical context Bertrand's postulate, also later known as Chebyshev's theorem, is a very important theorem in number theory ...

10 months ago

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Perimeter of a semicircle
Given the diameter d, find the perimeter of a semicircle

10 months ago

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Return unique values without sorting
If the input vector A is [42 1 1], the output value B must be the unique values [42 1] The values of B are in the same order a...

10 months ago

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First non-zero element in each column
For a given matrix, calculate the index of the first non-zero element in each column. Assuming a column with all elements zero i...

10 months ago

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Getting the indices from a matrix
Inspired by Problem 645. Getting the indices from a matrix. Given a matrix A (or a vector), return the indices (always in row...

10 months ago

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Determine if input is a perfect number
A perfect number occurs whent the sum of all divisors of a positive integer, except the number itself, equals the number. Examp...

10 months ago

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First N Perfect Squares
*Description* Return the first N perfect squares *Example* input = 4; output = [ 1 4 9 16 ];

10 months ago

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Determine the number of odd integers in a vector
Determine the number of unique odd integers in a vector. Examples: Input x = [2 5 8 3 7 1]; Output y = 4; Inp...

10 months ago

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Unique values without using UNIQUE function
You must return unique values in a vector in *stable* mode without using the unique function. About stable order flag: ...

10 months ago

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Find nth maximum
Find nth maximum in a vector of integer numbers. Return NaN if no such number exists. x = [2 6 4 9 -10 3 1 5 -10]; So ...

10 months ago

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Create an index-powered vector
Given a input vector x, return y as index-powered vector as shown below. Example x = [2 3 6 9] then y should be [...

10 months ago

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Find last zero for each column
Given a numeric array of arbitrary size, return the row index of the last zero for each column. If a column contains all nonzero...

10 months ago

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Calculate the Number of Sign Changes in a Row Vector (No Element Is Zero)
For a row vector: V=[7 1 2 -3] there is one sign change (from 2 to -3). So, the function you write must return N=1. F...

10 months ago

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Symmetry of vector
Determine whether the vector is symmetric or not (vector could be even or odd in length). For example: x = [1 2 3 3 2 1] is s...

10 months ago

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Find Rows with Specift Properities
Delete rows with specific properites as following: Find rows that have a negative value in any element of the row and delete it...

10 months ago

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Tridiagonal
Return an n-by-n matrix that has a, b, c as the subdiagonal, main diagonal, and superdiagonal entries in the matrix. Example ...

10 months ago

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Find the maximum two numbers of every column of a matrix
Find the maximum two numbers of every column of a matrix. Example: If we input a matrix A = [ 1 2 4 6 0 3 ...

10 months ago

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How unique?
Sometimes, when we check unique entries of vector we would like to know how many times each value occurs. Given vector of num...

10 months ago

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Another colon problem
This is simple problem based on problems 555, 801, 1118, etc. Create an index vector from two input vectors. Example: ...

10 months ago

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Sum of odd numbers in a matrix
Find the sum of all the odd numbers in a matrix. Example x = [2 3 5 7 1 4 11] y = 27

10 months ago

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Find the index of n in magic(n)
If input n=5, then magic(n) is 17 24 1 8 15 23 5 7 14 16 4 6 13 20 22...

10 months ago

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Replace pattern 0 1 0 and 1 0 1
Find and replace a pattern in a row of zeroes and ones. * Find 1 0 1 and replace it with 1 1 1 * Find 0 1 0 and replace it w...

10 months ago

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counting groups!
This problem is about counting groups. Example If you have x: x = [0.8 0.8 0.8 0.3 0.3 0.4 0.5 0.6 0.6 0.9] then a...

10 months ago

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expand intervals
You're given a row vector of an even number of monotonically increasing integers. Each pair of consecutive integers is the lower...

10 months ago

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compress sequence into intervals
You're given a row vector of monotonically increasing integers most of which are consecutive. Find the upper and lower bounds of...

10 months ago

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expand intervals vol.2
Similar to problem <http://www.mathworks.co.uk/matlabcentral/cody/problems/2528 2528>. This is a more general case, when bounds ...

10 months ago