243 total contributions since 2012

As a small child I was always taking things apart and putting them back together... things haven't changed.

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Make a random, non-repeating vector.

This is a basic MATLAB operation. It is for instructional purposes. --- If you want to get a random permutation of integer...

7 months 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.

7 months ago

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Generate a vector like 1,2,2,3,3,3,4,4,4,4

Generate a vector like 1,2,2,3,3,3,4,4,4,4 So if n = 3, then return [1 2 2 3 3 3] And if n = 5, then return [1 2 2...

7 months ago

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Number of 1s in a binary string

Find the number of 1s in the given binary string. Example. If the input string is '1100101', the output is 4. If the input stri...

7 months ago

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Return the first and last character of a string

Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

7 months ago

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Getting the indices from a vector

This is a basic MATLAB operation. It is for instructional purposes. --- You may already know how to <http://www.mathworks....

7 months ago

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Maximum value in a matrix

Find the maximum value in the given matrix. For example, if A = [1 2 3; 4 7 8; 0 9 1]; then the answer is 9.

7 months ago

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Some Assembly Required

The input to this function is a matrix of real numbers. Your job is to assemble the rows of the matrix into one large row that ...

1 year ago

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Operate on matrices of unequal, yet similar, size

You may want to add a vector to a matrix, implying that the vector is added to each column of the matrix. Or multiply a 3x4x5 ma...

1 year ago

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N-Dimensional Array Slice

Given an N-dimensional array, _A_, an index, _I_, and a dimension, _d_, return the _I_ th elements of _A_ in the _d_ dimension. ...

1 year ago

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Permute diagonal and antidiagonal

Permute diagonal and antidiagonal For example [1 2 3;4 5 6;7 8 9] -> [3 2 1;4 5 6;9 8 7] WITHOUT diag function (and variable n...

1 year ago

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Matrix with different incremental runs

Given a vector of positive integers a = [ 3 2 4 ]; create the matrix where the *i* th column contains the vector *1:a(i)...

1 year ago

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surrounded matrix

With a given matrix A (size m x n) create a matrix B (size m+2 x n+2) so that the matrix A is surrounded by ones: A = [1 2 ...

1 year ago

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Rotate input square matrix 90 degrees CCW without rot90

Rotate input matrix (which will be square) 90 degrees counter-clockwise without using rot90,flipud,fliplr, or flipdim (or eval)....

1 year ago

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Set some matrix elements to zero

First get the maximum of each *row*, and afterwards set all the other elements to zero. For example, this matrix: 1 2 3 ...

1 year ago

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Removing rows from a matrix is easy - but what about inserting rows?

Assume A is a 5-by-5 matrix. A([2,4],:) = [] is a quick way to remove rows 2 and 4. Can you find a quick way to insert rows into...

1 year ago

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Remove the air bubbles

Given a matrix a, return a matrix b in which all the zeros have "bubbled" to the top. That is, any zeros in a given column shoul...

1 year 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...

1 year ago

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Make an awesome ramp for a tiny motorcycle stuntman

Okay, given a vector, say v=[1 3 6 9 11], turn it into a matrix 'ramp' like so: m=[1 3 6 9 11; 3 6 9 11 0; 6 9 ...

1 year 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...

1 year 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 ...

1 year 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...

1 year 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...

1 year ago

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Side of a rhombus

If a rhombus has diagonals of length x and x+1, then what is the length of its side, y? <<http://upload.wikimedia.org/wikipe...

1 year ago

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Is this triangle right-angled?

Given any three positive numbers a, b, c, return true if the triangle with sides a, b and c is right-angled. Otherwise, return f...

1 year ago

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Area of an equilateral triangle

Calculate the area of an equilateral triangle of side x. <<http://upload.wikimedia.org/wikipedia/commons/e/e0/Equilateral-tr...

1 year ago

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Side of an equilateral triangle

If an equilateral triangle has area A, then what is the length of each of its sides, x? <<http://upload.wikimedia.org/wikipe...

1 year ago

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Triangle sequence

A sequence of triangles is constructed in the following way: 1) the first triangle is Pythagoras' 3-4-5 triangle 2) the s...

1 year ago

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Alphabetize by last name

Given a list of names in a cell array, sort the list by the last name. So if list = {'Barney Google','Snuffy Smith','Dagwood ...

1 year ago