# wei zhang

### USTC

PHD candidate in life science department

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**Content Feed**

Question

Why identifier "mxGetUint64s" is undefined in mex or cudamex?

Hi, I am trying to deal with unsigned long format arrays in mex. I found in mxGetUint64s page that I should use mxGetUint64s ins...

ungefär ett år ago | 1 answer | 1

### 1

answerHow could I compile with cuda/thrust library in cudamex?

The example could run well since 2021a.

ungefär ett år ago | 0

| accepted

Why `gpucoder.profile` example failed?

I should thank Matlab team first, especially Hu Halley and Erik. It is all about cupti library including as below. setenv('PATH...

mer än ett år ago | 0

| accepted

Solved

Times 2 - START HERE

Try out this test problem first. Given the variable x as your input, multiply it by two and put the result in y. Examples:...

mer än ett år ago

Question

Why `gpucoder.profile` example failed?

I am trying to profile the gpu code. At first, I tried the example in gpucoder.profile. But it always gives an error with someth...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

Could matlab use `nvprof` in cuda profiling?

I am using cudamex. I need to profile the time consuming. Is there any sample called "nvprof" with a ".m" file? Or could I use i...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

Is there a data size limited in the mex of cell format?

I am trying to pass some large cell arrays from mex to Matlab. I found it may stuck Matlab if the output cell array is large. Is...

mer än ett år ago | 0 answers | 0

### 0

answersQuestion

Why `mxGetField` could not be assigned to output of c mex?

I am learning to compile mex with struct. I found a confusing problem. When I use mxGetField to assign the output of my mex, the...

mer än ett år ago | 2 answers | 0

### 2

answersQuestion

How could I compile with cuda/thrust library in cudamex?

Hi, I am trying to build a mex with thrust library with the below code. I got an error. C:\Program Files\MATLAB\R2020b\extern\i...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

Why `sparse` function accumulate large sparse COO format matrix by index so fast?

Hi, I am dealing with "repeated COO format" sparse matrix. I try to "accumulate" it by its index efficiently. I am inspired by t...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

Could I pass a 'triangulation' class into mex?

Hi, I am trying to use mexcuda to accelerate some code with triangle mesh. I would like to use 'triangulation' class variable a...

mer än ett år ago | 2 answers | 0

### 2

answersQuestion

How to "free" or "destroy" pointer array of mxArray?

Hi, I am using mexCallMATLAB in mex. So I need to construct pointer array for multi input or output. Like the below tmp variabl...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

How to set all one gpuArray in mex?

Hi, I need to set a all-one double gpuArray. I think I could use mxGPUCreateGPUArray to initial it. But it seems mxGPUCreateGP...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

How to make two mxArray* scalar multiply each other?

Hi, I have a simple step of multiplying two double scalar variables in mex. Why not the type "mxDouble" support multiply? Must ...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

How to check the Bytes of gpuArray?

Hi, I am confusing in checking the Bytes of gpuArrays. It seems every varaible's Bytes is 4. Could I do something more to set ...

mer än ett år ago | 2 answers | 0

### 2

answersQuestion

How to change the class of mxArray double to int in c mex ?

Hi, I am trying to convert a double class mxArray to int. I don't know how to do that. My c code is like below. I would like t...

mer än ett år ago | 0 answers | 0

### 0

answersQuestion

Why built-in conjugated gradient solver for sparse linear matrix runs much faster than normal script, no matter GPU or CPU?

I am trying to profile the conjugated gradient method for Ax = b. A is a large sparse matrix. The conjugated gradient method cou...

mer än ett år ago | 0 answers | 0

### 0

answersQuestion

Could I use double precision with `cusparse` or `cublas` function in mexcuda.cu file?

Hi, I am trying to compile my .cu file with cudamex. In this file, I would like to write some functions in cusparse or cublas f...

mer än ett år ago | 0 answers | 0

### 0

answersQuestion

Could I use the `mxGPUArray` format data in the cuda kernel function?

I am new in compiling the mexcuda. I am trying to use the mxGPUArray as inputs of cuda kernel. My sample.cu code is as below. It...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

How `gpuArray` save sparse matrix when running Preconditioned conjugated gradient?

Hi, I am using cuda in Matlab to accelerate the Preconditioned conjugated gradient evaluation of "Ax = b". I'm glad to find the ...

mer än ett år ago | 1 answer | 0

### 1

answerQuestion

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...

nästan 2 år ago | 0 answers | 0

### 0

answersQuestion

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*...

ungefär 2 år ago | 3 answers | 0

### 3

answersHow 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...

ungefär 2 år 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...

ungefär 2 år ago | 3 answers | 0

### 3

answersQuestion

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...

ungefär 2 år ago | 1 answer | 0

### 1

answerQuestion

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. ...

ungefär 2 år ago | 1 answer | 0

### 1

answerQuestion

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...

ungefär 2 år ago | 1 answer | 1

### 1

answerQuestion

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...

ungefär 2 år ago | 3 answers | 0

### 3

answersQuestion

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...

ungefär 2 år ago | 3 answers | 0

### 3

answersQuestion

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...

ungefär 2 år ago | 2 answers | 0