Community Profile # Zhihao Wei

Last seen: Today Active since 2021

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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...

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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: ...

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Given a larger and smaller matrix, perform element-by-element multiplication on the smaller matrix and a sub-matrix of the large...

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Replace secondary diagonal elements of a square array
Replace all the secondary diagonal elements of the square array A with the number n Example: A = [1 2 3 4 5 6 ...

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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...

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Outer product of multiple vectors
In tensor algebra, it is often useful to define a tensor as a product of lower order tensors. Similarly, a multidimensional arra...

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System of equations
Find a solution to a system of equations represented by a |n| by |n+1| matrix. For instance, [ 2 0 4; => 2*x = 4 ...

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Determine if input is a valid AHP evaluation matrix
Input is a matrix. Output is a true or false statement (1 or 0). Return true if input is a valid Analytic Hierarchy Process eval...

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Projector Matrix
Write a function to determine whether or not the matrix is a projector. Projector matrices are defined as P^2 = P.

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Nilpotent matrix
Check if matrix A is <http://mathworks.com/ nilpotent>.

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Orthonormal matrix
You decide whether any given matrix is an orthonormal matrix or not. If each column in a matrix is perpendicular to the other...

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Is this matrix orthogonal?
Given a square matrix, a, determine whether it is orthogonal. INPUT: a, a n x n matrix OUTPUT: true or false

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Combined Ages 2 - Symmetric, n ≥ 3
Following on <http://www.mathworks.com/matlabcentral/cody/problems/42382-combined-ages-1-symmetric-n-3 Combined Ages 2>, you wil...

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Combined Ages 1 - Symmetric, n = 3
You have probably seen the common riddle wherein combined ages are provided and you must determine the individual ages. For exam...

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Solve the set of simultaneous linear equations
Given this pair of simultaneous linear equations: 2x + 3y = 23 3x + 4y = 32 Find the solution set (x,y)

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Linear system of equations
Solve the system of equations in three variables.

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Column norms of a matrix
Given a matrix M, return a vector y such that for each k y(k)=norm(M(:,k)) (y(k) is the Euclidean norm of the k-th col...

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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 ...

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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-...

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Toeplitize a matrix
Similar to <http://www.mathworks.com/matlabcentral/cody/problems/3094-hankelize-a-matrix Problem 3094. Hankelize a matrix>, now ...

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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>, ...

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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...

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Must be in the front row...
You are given a matrix followed by a single number. Your object is to write a script that will shift the matrix around so that ...

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Go to the head of the class!
You're given a matrix and a single number. If that number is in the matrix, reorder the matrix so that number is in the first r...

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Magnet and Iron
(Inspired from <http://www.mathworks.com/matlabcentral/cody/problems/112 Problem 112: Remove the air bubbles>) Iron (atomic n...

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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 ...

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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 ...

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Too Many Zeros, Dump Them!
Sometimes when I create a matrix, I use this syntax: a = zeros(1000,1000); But when the function ends, I find that I don'...

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A matrix of extroverts
Now that the introverts have had their script, the extroverts spoke up (naturally!) and demanded one as well. You will be given...