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Xh Du


Last seen: 2 years ago |  Active since 2015

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Try to save structural variable, but not everything is saved
Hi all, I ran my code for a few hours and now I get some results. I'd like to save these data to a .mat file such that I can ...

7 years ago | 1 answer | 0

1

answer

Question


Is it faster to operate a sparse matrix than a dense one when they have the same size?
Hi all, Imagine I have 2 same size matrices, both takes only the upper triangular part and sparse, their sparsity is like thi...

7 years ago | 2 answers | 0

2

answers

Question


How to recover a square matrix from its upper triangular cell part?
Hi all, I'd like to compute the upper triangular part only for a symmetric matrix in a block by block way. After some operat...

7 years ago | 1 answer | 0

1

answer

Question


Put elements into corresponding locations of upper triangular matrix
Hi all, Imagine I have a vector: inpt = (1:6)'; Now I'd like to put elements of inpt in the upper triangular part of ...

7 years ago | 2 answers | 0

2

answers

Question


How to compute the indices of a square matrix?
Hi all, Imagine I have indices: i, j, k, l, I write for i = 1:1 for j = 1:1 for k = 1:2 for l = 1:2 ...

7 years ago | 2 answers | 0

2

answers

Question


Operations for calculating l1 and Frobenius norm
Hi all, Imagine I have 2 same-length vectors, u1 and u2, and e = u1 - u2. I'd like to calculate 1. l1 norm of e; 2. Frobenius...

7 years ago | 1 answer | 0

1

answer

Question


Fprintf: how to automatically move to a new line when reach end of screen?
Hi all, I have something like this: clear; clc; for i = 1:100 fprintf('%d', i) end Here I use fprintf to...

7 years ago | 5 answers | 0

5

answers

Question


How to plot the l2 norm circle?
Hi all, I'm trying to visualize the l2 norm circle. It seems easy but I'm stuck. This is the code I write to plot the circle ...

7 years ago | 1 answer | 0

1

answer

Question


Concatenate cell array along one dimension
Hi all, I have a cell array like this: cellA = [12x2 double] [12x2 double] [12x2 double] [12x2 doub...

7 years ago | 1 answer | 0

1

answer

Question


Extract and realign cells into new cell
Hi all, I have a cell array 'cellA' which contains cell: cellA = {2x1 cell} {2x1 cell} {2x1 cell} {...

7 years ago | 1 answer | 0

1

answer

Question


Optimize RAM cost by only storing upper triangular part of a symmetric matrix?
Hi all, I have some symmetric (almost dense) matrices which I wish to store only the upper triangular part such that I can op...

7 years ago | 2 answers | 0

2

answers

Question


Lagrange interpolation in 2D?
Hi all, I'd like to find the interpolating polynomials on a 2d domain. Imagine we have sample points (x1, y1), ... ,(xn, ...

7 years ago | 1 answer | 0

1

answer

Question


MATLAB killed in Linux
Hi all, I'm running my code with a elasto-dynamics model, which has 300 degrees of freedom and 300 time steps, and this probl...

7 years ago | 0 answers | 0

0

answers

Answered
Dynamically update cell without clearing previous content?
solution: 'a' can be dynamically updated without special treatment: clear; clc; nr = 1; a = cell(1); for i...

7 years ago | 0

| accepted

Question


Dynamically update cell without clearing previous content?
Hi all, I'd like to dynamically update cell content and size, without clearing the previous cell content. Check the following...

7 years ago | 1 answer | 0

1

answer

Question


How to plot solid tetrahedrons in MATLAB?
Hi all, I have information of a mesh including coordinates of nodes and connectivity, how can I plot solid tetrahedrons in MA...

7 years ago | 2 answers | 0

2

answers

Question


Any recommendations for 3d FEM toolboxes in MATLAB?
Hi all, I have a finite element mesh including nodes and connectivity imported from Abaqus, which looks like this: >> ca...

7 years ago | 0 answers | 0

0

answers

Question


Variable size: does it reflect real size after computation finishes?
Hi all, I have a program which produces a 40227 by 50 double matrix. I'd like to optimize storage so I want to check total me...

7 years ago | 2 answers | 0

2

answers

Question


Built-in functions VS explicit loops: which is faster in MATLAB?
Hi all, I did some speed tests with implicit functions and explicit loops, both repeat 1000 times and calculate average time....

7 years ago | 0 answers | 0

0

answers

Question


Avoid for loops, use cell operation
Hi all, I've asked this question before but didn't get satisfied answer, so I'll change the way of asking. Say I have an ...

7 years ago | 1 answer | 0

1

answer

Question


Avoid for loops, use cell operation to do: r2' * r1 * l1' * l2
Hi all, Say I have 2 simple 1-by-2 cells, I'd like to perform operation like this: r2' * r1 * l1' * l2 to obtain a 2-by-2 mat...

7 years ago | 0 answers | 0

0

answers

Question


Surface plot with semilog z-axis: how to keep the same axis limit for iterative plots?
Hi all, I have an algorithm which generates 4 surfaces iteratively. I'd like to set the z-axis to semilog scale and keep the...

7 years ago | 1 answer | 1

1

answer

Question


How to only perform the upper triangular part of matrix operations?
Hi all, I'm trying to solve this problem, where I have to use a nested loop like this: clear; clc; demo = zeros(4, 4)...

7 years ago | 1 answer | 0

1

answer

Answered
How to avoid repeated computation when the result is a symmetric matrix?
Guess answer is in the comment, credit: Adam. https://uk.mathworks.com/matlabcentral/answers/332568-how-to-avoid-repeated-com...

7 years ago | 0

| accepted

Question


How to avoid repeated computation when the result is a symmetric matrix?
Hi all, When obtaining a symmetric matrix, we know that we only need to compute and store the elements of upper triangular pa...

7 years ago | 1 answer | 0

1

answer

Question


Cellfun to extract arrays from multi-dimensional cell
Hi all, Imagine I have a 2-d cell, each cell element is a m by n matrix, I apply SVD on each element such that they are decom...

7 years ago | 1 answer | 0

1

answer

Question


Cell in cell in cell...... versus multiDimensional cell
Hi all, Imagine now I have some data to be stored, say there are 24 matrices I need to store. I have 2 choices: 1. use cel...

7 years ago | 2 answers | 0

2

answers

Question


How to use savefig to save .fig to a specific location?
Hi all, I'd like to use savefig to save .fig files to a specific location, such as: savefig('test.fig') to here: ...

7 years ago | 1 answer | 0

1

answer

Question


How to find out the dependency of functions?
Hi all, For a function, I'd like to find out which scripts and functions are calling it. For example, there is a function: ...

7 years ago | 2 answers | 0

2

answers

Question


How to communicate among objects from different classes in a solid way?
Hi all, This is a really long question, thanks for your patience! Imagine I have two classes like this: classdef beam...

7 years ago | 1 answer | 0

1

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