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# Chi Zhang

79 total contributions since 2017

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Find the index of n in magic(n)
If input n=5, then magic(n) is 17 24 1 8 15 23 5 7 14 16 4 6 13 20 22...

etwa ein Monat ago

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Sum of odd numbers in a matrix
Find the sum of all the odd numbers in a matrix. Example x = [2 3 5 7 1 4 11] y = 27

etwa ein Monat 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

etwa ein Monat 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...

fast 2 Jahre 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)....

fast 2 Jahre 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 ...

fast 2 Jahre 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 ...

fast 2 Jahre 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...

fast 2 Jahre 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...

fast 2 Jahre 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 ...

fast 2 Jahre 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...

fast 2 Jahre 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...

fast 2 Jahre 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...

fast 2 Jahre ago

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Symmetry of vector
Determine whether the vector is symmetric or not (vector could be even or odd in length). For example: x = [1 2 3 3 2 1] ...

fast 2 Jahre ago

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Decimation - Optimized for speed
This problem is similar to http://www.mathworks.com/matlabcentral/cody/problems/1092-decimation, only this time the score will b...

fast 2 Jahre ago

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Decimation
When dealing to the Roman Army, the term decimate meant that the entire unit would be broken up into groups of ten soldiers, and...

fast 2 Jahre ago

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Implement a bubble sort technique and output the number of swaps required
A bubble sort technique compares adjacent items and swaps them if they are in the wrong order. This is done recursively until al...

fast 2 Jahre ago

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Reference Index Number
Given a reference set R of elements (each unique but identical in type), and a list V of elements drawn from the set R, possibly...

fast 2 Jahre ago

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Count consecutive 0's in between values of 1
So you have some vector that contains 1's and 0's, and the goal is to return a vector that gives the number of 0's between each ...

fast 2 Jahre ago

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Oh Zero Zero Zero!!!
Hello all, So you have to find the largest section of zeros in a vector and then find the length of those zeros and there start...

fast 2 Jahre ago

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Set a diagonal
Given a matrix M, row vector v of appropriate length, and diagonal index d (where 0 indicates the main diagonal and off-diagonal...

fast 2 Jahre ago

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Calculate the Number of Sign Changes in a Row Vector (No Element Is Zero)
For a row vector: V=[7 1 2 -3] there is one sign change (from 2 to -3). So, the function you write must return N=1. F...

fast 2 Jahre ago

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Unique values without using UNIQUE function
You must return unique values in a vector in *stable* mode without using the unique function. About stable order flag: ...

fast 2 Jahre ago

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Create an n-by-n null matrix and fill with ones certain positions
The positions will be indicated by a z-by-2 matrix. Each row in this z-by-2 matrix will have the row and column in which a 1 has...

fast 2 Jahre ago

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Find last zero for each column
Given a numeric array of arbitrary size, return the row index of the last zero for each column. If a column contains all nonzero...

fast 2 Jahre ago

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Max index of 3D array
Given a three dimensional array M(m,n,p) write a code that finds the three coordinates x,y,z of the Maximum value. Example ...

fast 2 Jahre ago

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Finding peaks
Find the peak values in the signal. The peak value is defined as the local maxima. For example, x= [1 12 3 2 7 0 3 1 19 7]; ...

fast 2 Jahre ago

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Find nth maximum
Find nth maximum in a vector of integer numbers. Return NaN if no such number exists. x = [2 6 4 9 -10 3 1 5 -10]; So ...

fast 2 Jahre ago

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Change the sign of even index entries of the reversed vector
change the signs of the even index entries of the reversed vector example 1 vec = [4 -1 -2 9] ans = [9 2 -1 -4] example2...

fast 2 Jahre ago

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Create an index-powered vector
Given a input vector x, return y as index-powered vector as shown below. Example x = [2 3 6 9] then y should be [...

fast 2 Jahre ago