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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...

3 months ago

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Hankelize a matrix
Similar to <http://www.mathworks.com/matlabcentral/cody/problems/42501-toeplitize-a-matrix Problem 42501. Toeplitize a matrix>, ...

3 months ago

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Convert matrix to 3D array of triangular matrices
Given a 2D numeric array x in which each column represents the vectorized form of an upper triangular matrix, return a 3D array ...

3 months ago

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matrix zigzag
Unfold a 2-D matrix to a 1-D array in zig-zag order, e.g., for matrix [ 1 2 3 ; 4 5 6 ; 7 8 9 ] the resulting 1-...

3 months ago

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Write a function man that takes a row vector v and returns a matrix H as follows..
Write a function called man that takes a row vector v as an input and returns a matrix H whose first column consist of the eleme...

3 months 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...

3 months 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...

3 months 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...

3 months ago

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Divide elements by sum of elements
In this problem, I ask you to write a function which will divide the elements of each column by the sum of the elements of the s...

3 months ago

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Vector to 3-Column Matrix
Consider a vector *A* such as A = [1 2 3 3 4 5 6] Can you convert this vector to a three-column matrix like this: ...

3 months ago

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Product of Each Column
Given a matrix |mat| with |n| columns, return a row vector |v| of length |n|, where every element in |v| is the product of the |...

3 months ago

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Concatenated roots
Which is the value of this infinte concatenated roots? <<https://s27.postimg.org/i4hkin7xf/Code_Cogs_Eqn.gif>> Note: If ...

3 months ago

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calculate PI without using pi function
There are many methods to get the pi(Ratio of circumference to diameter). You should get pi without using the pi function in M...

3 months ago

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Calculate the hypotenuse of a right triangle without using ^ and sqrt ()
Find out the hypotenuse of right triangle. Say a = 4, b = 3 then c = 5 Please don't use ^ and sqrt() function.

3 months ago

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Airline Ticket Mod7 Checksum
There are 13 digits in an airline ticket number. If an airline ticket number is valid, the 13th digit should be the remainder of...

3 months ago

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Raise a polynomial to a power
In Matlab, polynomials are represented by a vector of coefficients. For example, the polynomial p=a*x^2 + b*x + c is represente...

3 months ago

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Make an N-dimensional Multiplication Table
*INSTRUCTIONS* This is a multi-dimensional variant of the normal multiplication table used to teach elementary students multi...

3 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...

3 months ago

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Find x rows where the sum of the numbers is the maximum
Find x rows where the sum of the numbers is the maximum. For example: when x is 2 and m is 2 3 5 0 2 3 5 5 6 0 9 4 then y =...

3 months ago

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Symmetric matrix
You must create a n-by-n *symmetric* matrix such that A(row,col) = row/col for col >= row. Example if n =3 : output is : ...

3 months ago

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Create Volcano (or Atoll) martix. It is an extension of Bullseye matrix problem.
For example, if n=2 (maximum value), the output matrix should be [1 1 1 1 1; 1 2 2 2 1; 1 2 1 2 1; 1 2 2 2 1; 1 1 ...

3 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.

3 months ago

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Triangular matrices in 3D array
Given a 3D numeric array _x_, return an array _y_ of the same size in which all entries to the right of the main diagonal are ze...

3 months ago

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Numbers spiral diagonals (Part 1)
Inspired by Project Euler n°28 et 58. A n x n spiral matrix is obtained by starting with the number 1 and moving to the right...

3 months ago

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Matrix Construction I
Given n, construct a matrix as shown in the example below. Example For n=8, the output should look like this: 1 2 3 4 ...

3 months ago

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Rainbow matrix
Create a "rainbow matrix" as described in the following examples Input = 3 Output = [ 1 2 3 2 3 2 ...

3 months ago

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BULLSEYE Part 2: Reference Problem 18 BULLSEYE
Given n (always odd), return output a that has concentric rings of the 1s and 0s around the center point. Examples: Input ...

3 months ago

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Approximation of Pi
Pi (divided by 4) can be approximated by the following infinite series: pi/4 = 1 - 1/3 + 1/5 - 1/7 + ... For a given number of...

3 months ago

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Diagonal Pattern
For a positive integer |n|, return an |nXn| matrix |mat| such that the value of each element in row |i| and column |j| is given ...

3 months ago

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Make a rainbow matrix (follow-up to checkerboard matrix)
Given an integer n, make an n-by-n matrix as shown below. The a(1,1) should be 0. As we move away from the top-left, the number ...

3 months ago

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