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Matt J


Last seen: Today Active since 2009

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Professional Interests: medical image processing, optimization algorithms PLEASE NOTE: I do not read email sent through my author page. Please post questions about FEX submissions in their respective Comments section.

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  • Most Accepted 2022
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Answered
Unable to achieve desired speed up using parfor
I find that all instances on B finish in about half the time as those on A. It baffles me... That is the expected result, assu...

2 days ago | 0

Solved


Sum All Positive Elements
Output a scalar that is equal to the sum of all positive elements in a given vector/matrix. For Example: The sum of all positi...

2 days ago

Solved


Build a block Toeplitz matrix
A symmetric block Toeplitz matrix has the form, where the are compatibly-sized matrices. Write a routi...

2 days ago

Answered
How to avoid unrecognized option names using optimget
Although I am using R2024a, that particular code still uses an older (2016-2019) version of lsqcurvefit. If so, problem solved....

3 days ago | 0

| accepted

Problem


Build a block Toeplitz matrix
A symmetric block Toeplitz matrix has the form, where the are compatibly-sized matrices. Write a routi...

3 days ago | 0 | 4 solvers

Answered
Finding the Center of Broken Vase Slices
You can use ellipticalFit() from this download, https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tool...

3 days ago | 1

Problem


Condition number of Kronecker product
Given NxN matrix A and MxM matrix B, where M,N<=1000, write a routine to compute the condition number of kron(A,B).

3 days ago | 0 | 2 solvers

Solved


2x2 binning of a large sparse matrix
Consider the 20000 x 20000 sparse matrix, A=round(sprand(2e4,2e4,1/1e4*100)*1000); The task is to divide this matrix into 2x...

5 days ago

Solved


Convert a vector into numbers
Suppose a vector x = [ 1 2 4 7] is given. You have to convert this vector into string number y = '1247'. Examples x = [ 1...

6 days ago

Solved


Reverse within string
If input is a string 'yellow' the output should be 'leywol'. Locate the middle of the string and reverse the first (yel) and sec...

6 days ago

Solved


Minimum Distance Point to Segment
This Challenge is to determine the minimum distance from a 2-D line segment defined by two points to a point. The point is (p...

6 days ago

Solved


Property dispute!
Two neighbors have rectangular plots of land A and B. The surveyors give you the coordinates of each. If they overlap, there is ...

6 days ago

Solved


Project Euler: Problem 10, Sum of Primes
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below the input, N. Thank you <http:/...

6 days ago

Solved


Extract diagonal of sparse quadratic form
Consider the matrix A and vector v given by, A=round(sprand(5e3,1e4,1/1e4*100)*100); v=randi(10,width(A),1); Write a rout...

6 days ago

Problem


Extract diagonal of sparse quadratic form
Consider the matrix A and vector v given by, A=round(sprand(5e3,1e4,1/1e4*100)*100); v=randi(10,width(A),1); Write a rout...

6 days ago | 1 | 4 solvers

Problem


2x2 binning of a large sparse matrix
Consider the 20000 x 20000 sparse matrix, A=round(sprand(2e4,2e4,1/1e4*100)*1000); The task is to divide this matrix into 2x...

7 days ago | 0 | 4 solvers

Solved


Do the line-segments intersect?
You are given two line segments. Do they cross? Consider one segment as (x1,y1) to (x2,y2), the other segment as (x3,y3) to (x4...

7 days ago

Solved


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...

7 days ago

Solved


Flipping
Write code that can reverse the vector without using any sort of loop. Example Given the input vector A = [ 1 2 3 4 5...

7 days ago

Solved


Flip the diagonal values
Write a program that flip the elements of main diagonal , upper and lower diagonal values of a sqare matrix. For example if a ...

7 days ago

Solved


Flip the bit
Given an input character string (e.g. '1001'), return a character string with the bits flipped ('0110').

7 days ago

Solved


Flipping a Matrix
Flipping matrix up and down. If a central row is exists, leave it, and flip remaining rows. Example Mat = magic(3) ...

7 days ago

Solved


Swap two numbers
Example Input: a = 10 b = 20 Output a = 20 b = 10

7 days ago

Solved


Half-Swap
Given a vector with an even number of elements, rearrange it so that the elements in its first half are switched with those i...

7 days ago

Solved


Matlab Basics - Switching Assignments
Switch assignments for variables x and y, for example start with x = 1 and y = 3 end with y = 1 and x = 3 Do NOT simply r...

7 days ago

Solved


Swap between columns
The idea is to swap between second and second last column Ex = [1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; ...

7 days ago

Solved


Remove a specific character with another
Remove any (-) dash sign with (_) underscore Ex = 'The-Journey-of-thoudsands-miles-starts-with-a-single-step' y = 'The_Jour...

7 days ago

Solved


Swap between first and last
The idea is to swap between first and last row Ex = [1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; ...

7 days ago

Solved


Swap between first and last column
The idea is to swap between first and last column Ex = [1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; 1 2 3 4 5; 1 2 3 ...

7 days ago

Solved


Swap between rows
The idea is to swap between second and second last row Ex = [1 2 3 4 5; 5 4 3 2 1; 1 2 3 4 5; 1 2 3 4 5; ...

7 days ago

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