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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...

7 years 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...

7 years 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)...

7 years 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 ...

7 years 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)....

7 years ago

Solved

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 ...

7 years 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 ...

7 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...

7 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 ...

7 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...

7 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...

7 years ago

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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 ...

7 years ago

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Largest territory
Determine whose territory is largest. If there are multiple numbers tied for the largest territory, return the smallest number. ...

7 years ago

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Finding neighbors of [-1:1] in a matrix....
Hello All! Well I found this one fun to figure out, all you have to do is make a matrix of 1's or 0's (true or false) that sh...

7 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...

7 years ago

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expand intervals vol.3
This is the next problem after <http://www.mathworks.co.uk/matlabcentral/cody/problems/2528 2528> and <http://www.mathworks.co.u...

7 years 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...

7 years ago

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return row and column indices given 2 values which define a range
Inspired by problem <http://www.mathworks.co.kr/matlabcentral/cody/problems/856-getting-the-indices-from-a-matrice> Inputs: - ...

7 years ago

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remove single elements
Given a vector of integers, remove the elements that have appeared only once. The output elements should be in exact order as th...

7 years 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 ...

7 years 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...

7 years 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...

7 years 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...

7 years 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...

7 years 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 ...

7 years 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...

7 years 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: ...

7 years 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 ...

7 years ago

Solved

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...

7 years ago

Solved

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 ...

7 years ago