Question

How to quickly find the first non-zero element without iterations in all columns in a sparse matrix?

Hi, All, I have a big sparse matrix A. I want to find out the first non-zero element in all columns from the top. Here is my co...

12 months ago | 4 answers | 0

Question

How to quickly find the maximum group of same rows in a matrix?

Dear All, I have a matrix and there exist identical rows in the matrix. I want to find the maximum group of identical rows in t...

1 year ago | 1 answer | 0

Question

Looking for a code in Matlab optimization

Dear All, I do not know if a code exists in Matlab optimization for the following integer linear programming. Min ||A*x - b|...

1 year ago | 1 answer | 0

Question

How to improve the accuracy of lu decomposition?

Dear All, I did the following calculation and found lu decomposition is Not accurate as I expected. For a set of linear equatio...

1 year ago | 3 answers | 0

Question

How to fix an error in Parallel Processing?

Dear All, When I tried to use parfor to run my code, I always got the following error message (I defined the variable "red" at ...

1 year ago | 0 answers | 0

Question

Problems encountered in Parallel Processing

Dear All, I tried to use parfor to run my code which is given as follows: function [A,B] = temp_test(x) a = [1:2*x]; b = [1:x...

1 year ago | 1 answer | 0

Question

Can we calculate the roots of polynomials with matrix coefficients?

Dear All, I have a polynomial which has matrix coefficients. For example, I have the following equation: [1 0;0 1]*[x_1^2; x_2...

1 year ago | 1 answer | 0

Question

A Question About the exe file generated by Matlab Compiler

Dear All, If I generate an exe file using Matlab Compiler, can I still use this exe file after Matlab Compiler gets expired? Wh...

1 year ago | 1 answer | 0

Question

How to solve a special linear equation Ax=b? A is a row vector.

Dear All, I am trying to solve the following linear equation Ax=b: [a1 a2 ... an][x1 x2 ... xn]' = b. where b is a complex num...

1 year ago | 2 answers | 1

Question

How to display a matrix which has elements with big difference in values?

Hi, All, I want to display a matrix A which has elements with big difference in values. For example, A=[1000 0.2;1001 0.5;2120 ...

2 years ago | 1 answer | 0

Question

The fastest way to check if a sparse matrix is singular or not?

Dear All, For a large sparse matrix A, how can I check in a fastest way if matrix A is singluar or not? The matrix has a dimens...

2 years ago | 1 answer | 0

Question

How to find the last nonzero entry in all rows of a sparse matrix?

Dear All, I need to find out the last nonzero entry in each row of a sparase matrix A. Say A=[1 3 0 0 0 0;0 4 2 3 0 0;5 0 0 1 4...

2 years ago | 1 answer | 0

Question

Is there a faster approach than \ operator to calculate the inverse of a lower triangular matrix?

Dear All, I have a big square lower triangular matrix A (6000 x 6000) which is very sprase with a density 0.05%, I am using Inv...

2 years ago | 0 answers | 0

Question

Efficient Inverse of a updated lower triangular matrix

Dear All, I am looking for the inverse of a updated lower triangular matrix. The original matrix is A which is a lower triangul...

2 years ago | 0 answers | 0

Question

How to find out the location difference of nonzero entries in two sparse matrices?

Hello, All, I have two sparse matries which have the same size. I know every nonzero entry in A must correspond to a nonzero ...

2 years ago | 1 answer | 0

Question

How to do a quick division between a column array and a matrix?

Hello, All, I want to divid a column array b (N x 1) by each column in a big sparse matrix A (N x M). My code is as follows: ...

2 years ago | 1 answer | 0

Question

How to design a professional output format?

Hi, All, I am going to submit a final report of project. I want to design a professional output format. I do not know if anyo...

2 years ago | 0 answers | 0

Question

How to display the code is running?

Hi, All, I have a code which takes several minutes to finish the execuation. I donot want to display the middle results on th...

2 years ago | 2 answers | 0

Question

How to obtain the minimum square full rank sub-matrix in a sparse matrix?

Dear All, For a given sparse matrix, I am looking for the minimum square full-rank sub-matrix which is formed by nonzero column...

2 years ago | 1 answer | 1

Question

How to quickly combine some lines in a network?

Dear All, For a given network formed by edges and lines, I want to combine some lines in this network to generate a new netwo...

2 years ago | 0 answers | 0

Question

Looking for all sub-networks among a network

Dear All, For a given network formed by lines and edges, how can I quickly find out all sub-networks? There is no connection ...

2 years ago | 1 answer | 0

Question

How to solve this weird problem in Matlab?

Dear all, I have a linear equation: a*x1-b*x2+x3=1.0. a and b are known parameters: a=b=10E+6. Now we know the solutions of x...

2 years ago | 2 answers | 0

Question

Faster approach of LU decomposition for a symmetric sparse matrix than lu in Matlab?

Dear All, I have a symmetric sparse matrix A. I want to obtain its LU decomposition. But I found lu(A) took me about 1 second...

2 years ago | 1 answer | 0

Question

Faster inverse of a lower triangular matrix than inv(A)?

Dear All, I have a sparse lower triangular matrix A. I want to obtain the inverse of A. A has a size of 6000 X 6000. I find i...

2 years ago | 2 answers | 0

Question

How to assign values to a sparse matrix without iterations?

Hi, All, I want to assign non-zero values to a matrix H. I know the locations of all the non-zeros. For example, I know the n...

2 years ago | 2 answers | 0

Question

How to specifically select columns from a matrix?

Dear All, For a given 2 columns matrix A. For example <</matlabcentral/answers/uploaded_files/135120/Screen%20Shot%202018-...

2 years ago | 1 answer | 0

Question

Semi-Lower Triangular Matrix

Dear All, I want to convert a general sparse matrix into a semi-lower triangular matrix. For example, a given matrix A: A=...

2 years ago | 0 answers | 1

Question

A challenging problem: how to obtain a semi-lower triangular matrix from a general matrix?

Dear All, I want to convert a general sparse matrix into a semi-lower triangular matrix. For example, a given matrix A: A=...

2 years ago | 1 answer | 1

Question

Error caused by that small difference between two number is divided by a very small number

We have a situation that the difference between two complex numbers is divided by a very small complex number. For example, the ...

2 years ago | 0 answers | 0

Question

Does Orthogonal Matching Pursuit have the problem of divergence?

I am using the Matlab code of OMP to solve a nonlinear problem. But I do not now if OMP has the problem of divergence. As to my ...

3 years ago | 0 answers | 0