Community Profile # wei zhang

### USTC

38 total contributions since 2016

PHD candidate in life science department

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Question

Is there any function like "specgraphhelper" existing in the 2019a or later version?
I had used a scripted named "select3d", which function is to select points in 3d figure. But when I update my Matlab to 2019a. T...

16 days ago | 0 answers | 0

### 0

Question

Is there any method to accelerate many small matrix and vector's "mldivide" (4*4)?
I am trying to solve many(4000000) mldivide evaluation. All of them are in the form of "x = A\b". A is a 4*4 matrix, and b is 4*...

1 month ago | 2 answers | 0

### 2

How to set the constraints of L0- norm in linear programming?
I found an answer to my own question. I transfer the problem to MILP problem. The idea is from stackExchange. If I make anythi...

2 months ago | 0

Question

How to set the constraints of L0- norm in linear programming?
(sorry, I miss the objective function before. I have edited it well) I am trying to set the L0-norm constraints, which give a c...

2 months ago | 3 answers | 0

### 3

Question

How to set the sum of the absolute value of variables as inequality matrix and vector in linear programming?
I am trying to solve a linear program with command "linprog". The inequality constrains has a sum of varaibles. e.g. I have 3 va...

2 months ago | 1 answer | 0

### 1

Question

Is there a way to get the max memory used when I run my script?
I am trying to solve a distributed large sparse linear equation. I found the size of the RAM is the limitation of my algorithm. ...

3 months ago | 1 answer | 0

### 1

Question

What is the cause of the error of "CPARDISO encountered an error in phase 22: Error code = -2."?
I am trying to solve a large sparse matrix equation Ax = b. A is in 700000*700000, and b is in 700000*500. I am using the distri...

3 months ago | 1 answer | 0

### 1

Question

Is there any way to accelerate the solving of a series of large sparse positive definite linear equations "Ax=b" with same "A" and different "b"?
I am trying to solve a series of the linear equations Ax=b. A is a large sparse positive definite matrix, in n*n. And b is a vec...

3 months ago | 3 answers | 0

### 3

Question

Is there any method to calculate the inverse of matrix which changed a few values?
I have a large sparse matrix A and have gotten its inverse matrix inv(A) . Then I need to change an element value to get a new m...

3 months ago | 3 answers | 0

### 3

Question

Is there any way to speed up the function `changem`?
I am doing some substitutions of the index of triangle mesh. After removing or selecting some points on the mesh, I need to "ret...

3 months ago | 0 answers | 0

### 0

Question

How to set the shadow in the trimesh figure?
I am trying to display surface mesh of the brain in Matlab. I used the delaunayTriangulation object and trimesh function. I need...

3 months ago | 0 answers | 0

### 0

Question

How to accelerate the process of `find` in large for loop ?
I have two arrays A,B. I want to find the index of every element of B in A. I'm sure that every element of B must appears in A t...

3 months ago | 2 answers | 0

### 2

Question

Problem with using `reshape` to reorder the matrix.
I am trying to reorder my matrix "by block" in columns. See the code below, it is a mini case of my problem. It only has 2 ...

3 months ago | 2 answers | 0

### 2

Question

Is it possible to accelerate the speed of saving data into files with parallel way?
I am trying to save data to files, i.e. txt file. The speed is very low. This step takes almost 80% time over my whole script. M...

3 months ago | 2 answers | 0

### 2

Question

Is there faster way to apply `det` function along the third dimension?
I am trying to calculate the det of many 4*4 matrix. I store the data in a matrix with shape 4*4*n. (n =4000000). I am using the...

3 months ago | 1 answer | 0

### 1

Question

How to get the diagonal point pairs of a 2D rectangle?
I am trying to find the diagonal point pair of an arbitrary input rectangle. i.e. A = [1,1]; B = [-1,-1]; C = [1,-1]; D = [-...

3 months ago | 1 answer | 0

### 1

Question

How to make delaunayTriangulation object from points and connectivity in 3D?
I am trying the tetramesh function. Before I plot the tetraheron mesh, I need to store the mesh in an delaunayTriangulation obje...

4 months ago | 1 answer | 0

### 1

Question

Could `distributed array` accelerate the speed of solving Linear Equations with Iterative Methods?
I am using Iterative Methods, like preconditioned conjugate gradients to solve large sparse linear equations(800,000*800，000). I...

4 months ago | 1 answer | 0

### 1

Question

How to install pardiso on matlab with `pthread` on windows?
I am trying to use PARDISO in Matlab on windows. I notice that some compile options may not availible for windows system. This i...

4 months ago | 0 answers | 0

### 0

Question

Is it possible to rewrite these equation set to matrix form?
I am dealing with some equation set to calculate coefficients b. The equation set is as below. The x y z are the inputs. b is ou...

4 months ago | 1 answer | 0

### 1

Question

How to `subs` with both scalar variable and arrays?
I am evaluating some expression with subs. I need to input a scalar variable and an array. But it always give errors as I substi...

4 months ago | 1 answer | 0

### 1

Question

How to calculate the syms with variable has the same name?
Hello, I am writing a function with an augument to receive some expression, like ' a>0', ' b<0' and 'a>0&b<0'. There are variab...

5 months ago | 1 answer | 0

### 1

Question

Is it neccessary to define the ChunkSize and Filters when using h5read?
I am using h5read to read some data from hdf5 file. In the Matlab examples, the properties, "ChunkSize" and "Filters", are set a...

5 months ago | 0 answers | 0

### 0

Question

Could I modify the string position in the"TextScatter3" function ?
I am using TextScatter3 function to descript my data points. But my add-on mesh block some of them. I need to define the positio...

5 months ago | 1 answer | 0

### 1

Question

How to convert solution of syms array to a normal array?
I am solving a series function, e.g. . I want to get the obviously. For my codes, b = 2; y = [1,2,3,4]; syms x [1 4] S =...

5 months ago | 1 answer | 0

### 1

Question

Does "live script" support "rotate3d" in the mlx file?
Could I rotate my 3D figure in the live script as in a figure? I ran rotate3d but it seems no change. My matlab version is ...

5 months ago | 1 answer | 0

### 1

Question

Is there any shortcut for go back to previous folder?
Sometimes I need to navigate among some folders. I need the "go back" in a convenient way, like "cd -". But, this is not support...

5 months ago | 2 answers | 1

### 2

Question

How to rotate 3d graph freely by x or y axis?
Hi, I am trying to view some 3d geometric surface file. I found a problem that I can't rotate the graph total freely. For exa...

12 months ago | 2 answers | 0

### 2

Question

How to change the Matlab panel color?
I found the color setting for editor and command line in the preference. But as for the background of panel of tools(file, varia...

1 year ago | 1 answer | 0

### 1

Question

Why is vectorization faster than the parallel computing？
I am trying to speed my code, which processing some big geometry surface. From scanning on the website, I found 2 way to optimiz...

1 year ago | 1 answer | 0