204 total contributions since 2015

Solved

Matrix multiplication across rows

Given matrix m, return matrix n such that, rows of n are result of multiplication of the rows of the input matrix Example ...

2 years 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 ...

2 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...

2 years ago

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Create a vector whose elements depend on the previous element

The idea is to create a vector A whose elements depend on the previous element : *A(i+1) = 2*A(i)+1* *2 Inputs*: - A : The...

2 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 ...

2 years ago

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Sum of series VII

What is the sum of the following sequence: Σ(km^k)/(k+m)! for k=1...n for different n and m?

2 years ago

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Sum of series VI

What is the sum of the following sequence: Σk⋅k! for k=1...n for different n?

2 years 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?

2 years 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?

2 years 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?

2 years 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?

2 years 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?

2 years ago

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Convert a vector into a number

This is a sub problem related to this problem: <http://www.mathworks.com/matlabcentral/cody/problems/621-cryptomath-addition>...

2 years ago

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Right and wrong

Given a vector of lengths [a b c], determines whether a triangle with those sides lengths is a right triangle: <http://en.wikipe...

2 years ago

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Magic is simple (for beginners)

Determine for a magic square of order n, the magic sum m. For example m=15 for a magic square of order 3.

2 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...

2 years ago

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Replace Nonzero Numbers with 1

Given the matrix x, return the matrix y with non zero elements replaced with 1. Example: Input x = [ 1 2 0 0 0 ...

2 years ago

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Back to basics 21 - Matrix replicating

Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix, generate an output matrix that consists o...

2 years ago

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03 - Matrix Variables 6

Make _fMat_ be a 5x3 matrix of random integers with values from -3 to 3 (Hint: use *randi*)

2 years ago

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03 - Matrix Variables 1

Make the following variable: <<http://samle.dk/STTBDP/Assignment1_3a.png>> A 9x9 matrix full of 2's (Hint: use *ones* o...

2 years ago

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Back to basics 7 - Equal NaNs

Covering some basic topics I haven't seen elsewhere on Cody. Given 2 input variables, output true if they are equal, false ot...

2 years ago

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Rotate a Matrix

Input a Matrix x, Output y is the matrix rotating x 90 degrees clockwise

2 years ago

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Compute a dot product of two vectors x and y

x and y are input vectors, d is a number and contains their dot product

2 years ago

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Back to basics - mean of corner elements of a matrix

Calculate the mean of corner elements of a matrix. e.g. a=[1 2 3; 4 5 6; 7 8 9;] Mean = (1+3+7+9)/4 = 5

2 years 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...

2 years ago

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Remove NaN ?

input -> matrix (n*m) with at least one element equal to NaN; output -> matrix(p*m), the same matrix where we deleted the enti...

2 years ago

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Sort rows of a matrix

Sort rows of matrix A in an ascending order according to the last column Example input: A = [1 2 3;7 8 9;4 5 6]; Exam...

2 years ago

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Remove entire row and column in the matrix containing the input values

Remove the entire row and column from the matrix containing specific values. The specified value can be a scalar or a vector. Fo...

2 years ago

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Given a 4x4 matrix, swap the two middle columns

If a = [1 2 3 4; 1 2 3 4; 1 2 3 4; 1 2 3 4]; then the result is ans = 1 3 2 4 1 3 2...

2 years ago