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Is A the inverse of B?
Given a matrix A and a matrix B, is A the inverse of B? >>A=[2,4;3,5]; >>B=[-2.5,2;1.5,-1]; >>isInverse...

11 years ago

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Reverse the elements of an array
Reverse the order of elements in an array: eg: input X = [ 1 2 3 ; 4 5 6 ; 7 8 9 ] o...

11 years ago

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Vectorize the digits of an Integer
Create a vector of length N for an integer of N digits. x=123045; x_vec=[1 2 3 0 4 5]; I happened upon a trick to do ...

11 years ago

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Sum the numbers on the main diagonal
Sum the numbers on the main diagonal of an n-by-n matrix. For input: A = [1 2 4 3 6 2 2 4 7]...

11 years ago

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The Answer to Life, the Universe, and Everything
A variation of a previous Hitchhiker's Guide to the Galaxy problem. *Inputs:* Life, the Universe, and Everything *Output:*...

11 years ago

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sum of non-primes
The sum of the non-primes below 10 is 1+4+6+8+9+10=38 Find the sum of all the non-primes below the input, N.

11 years ago

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Replace multiples of 5 with NaN
It is required to replace all values in a vector that are multiples of 5 with NaN. Example: input: x = [1 2 5 12 10 7] ...

11 years ago

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Which quadrant?
Given a complex number, output quadrant 'I' 'II' 'III' or 'IV' | II | I | ...

11 years 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 nu...

11 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]; ...

11 years ago

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Sorting
Assume that x is an n-by-2 matrix. The aim is to return the first column of x, but sorted according to the second column. Exa...

11 years ago

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Back to basics 17 - white space
Covering some basic topics I haven't seen elsewhere on Cody. Remove the trailing white spaces from the input variable

11 years ago

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Back to basics 26 - Keywords
Covering some basic topics I haven't seen elsewhere on Cody. Return a cell array of strings of all MATLAB keywords.

11 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...

11 years ago

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Replace May with April
For instance, if the input is input_str = 'The flowers may bloom in April'; then the output is output_str = 'The flo...

11 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...

11 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...

11 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 ...

11 years ago

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Count photos
Given n people, everyone must have pictures taken with everyone, each photo includes only two persons, please count the total nu...

11 years ago

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Make a 1 hot vector
Make a vector of length _N_ that consists of all zeros except at index _k_, where it has the value 1. Example: Input ...

11 years ago

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Wind Chill Computation
On a windy day, a temperature of 15 degrees may feel colder, perhaps 7 degrees. The formula below calculates the "wind chill," i...

11 years ago

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Solving Quadratic Equations (Version 1)
Quadratic equations have the form: ax^2 + bx + c = 0. Example: x^2 + 3x + 2 = 0, where a = 1, b = 3, and c = 2. The equation has...

11 years ago

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Who is the smartest MATLAB programmer?
Who is the smartest MATLAB programmer? Examples: Input x = 'Is it Obama?' Output = 'Me!' Input x = 'Who ?' Ou...

11 years ago

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Create a square matrix of multiples
Given an input, N, output a matrix N x N with each row containing multiples of the first element of each row. This also applies...

11 years ago

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Say something funny
Say something funny, or not. Your solution will be (fully automatically and objectively) scored based on how clever or funny ...

11 years ago

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Find the biggest empty box
You are given a matrix that contains only ones and zeros. Think of the ones as columns in an otherwise empty floor plan. You wan...

11 years ago

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Spot the outlier
All points except for one lie on a line. Which one is the outlier? Example: You are given a list of x-y pairs in a column ...

11 years ago

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Avalaible area: wall construction
You need to build a wall to enclose a certain area. Calculate the available area after you build the wall. Assumptions * ...

11 years ago

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Time Expansion
How can you slow down any discrete-time signal? Example Input original signal x. x = [1 2 3 -1 -2 -5 -4] We want t...

11 years ago

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The Tower of Hanoi
In the <http://en.wikipedia.org/wiki/Tower_of_Hanoi Tower of Hanoi problem> with 3 rods (1, 2 & 3), the goal is to move a tower ...

11 years ago