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James Tursa


3 017 total contributions since 2007

Interested in external applications, mex & engine applications with Fortran, C, C++, etc, particularly in the areas of speed improvement and memory management efficiencies.

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Answered
Error using mex: undefined reference for user build package
Try looking in the MATLAB/R2019a/extern/lib folder for versions of these files appropriate for your system. They might have slig...

6 jours ago | 0

Answered
Problem with MexFunction and MexGetPr
Impossible to answer without seeing the code for the functionsum( ) function. Maybe you could post that? Maybe all you need to...

7 jours ago | 0

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Answered
Unexpected numerical error in built-in cross product
When I calculate things from scratch, everything works to the expected precision. E.g., run this code: % From post rTAN = [6.2...

24 jours ago | 2

Answered
MEX crashes when called twice in succession (Same input)
Here is one cause of a crash: mwIndex *subs; subs[0]=1; subs[1]=1; You are dereferencing an uninitialized pointer on that se...

24 jours ago | 0

Answered
Change sign of descending values
Is this what you want? x = your vector of values d = [1;diff(x)]; x(d<0) = -x(d<0);

25 jours ago | 1

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Answered
Trouble with declaring function output
function data = importer

25 jours ago | 1

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Answered
how to iterate a matrix for multiple times
E.g., here is a possible outline n = 30; % the number of iterations M = rand(5,5); % some initial matrix for k=1:n M = 2...

25 jours ago | 1

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Answered
Using the dms2degree Command Sequentially to Populate an Array using a Sub-routine
With a for-loop, you need to use A in all of your indexing and use the [ ] brackets to form a vector input (and spell the functi...

25 jours ago | 0

Answered
Write a function called valid_date that takes three positive integer scalar inputs year, month, day. If these three represent a valid date, return a logical true, otherwise false. The name of the output argument is valid.
Looks like you are taking the same class as Rahul. Rather than repeat my answer here, I will simply direct you to the link: ht...

25 jours ago | 0

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Answered
sum of multiplication for a vector and matrix
result = sum(b*A);

25 jours ago | 1

Answered
I need some help in seeing where I am going wrong and how to proceed with writing a particular funciton for a MATLAB course I am taking please.
Some issues: n is a fixed input ... you should not be changing n inside your function. Get rid of that n = n + 1 statement. T...

25 jours ago | 1

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Answered
Use of int vs size_t in mex compilation of C-function dgemm.
If you are linking to the MATLAB supplied BLAS/LAPACK libraries, then all of the integer types being used for arguments to these...

27 jours ago | 0

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Answered
For loop to extract every 3rd column out of matrix and assign as variable name
Do not do this! This will only lead to headaches downstream in your code for processing these variables (you will need to use m...

28 jours ago | 1

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Answered
random generator on level of bytes
Generate random integers and then multiply them by 8 to guarantee that the result is divisible by 8. E.g., something like: max_...

environ un mois ago | 2

Answered
Calculate sum of series using for
Here is an outline to get you started: a = something; % you put a value here m = something; % you put a value here x = someth...

environ un mois ago | 1

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Answered
Decimal to Binary Conversion
E.g., bstream = reshape(b',1,[]); If you want characters, then bstream = char(reshape(b',1,[]) + '0');

environ un mois ago | 1

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Answered
How to output a vector/array from a created function
Don't use size(inputVector) for your loop indexing limits since this is a vector. Use numel(inputVector) instead. Also, you sho...

environ un mois ago | 0

Answered
Cpp to Mex conversion
Looks like you have a mismatch with variable types, probably an older piece of code that you are trying to compile on a newer MA...

environ un mois ago | 1

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Submitted


mxGetPropertyPtr & mxSetPropertySDC C-mex functions
Fast memory efficient alternative to API functions mxGetProperty & mxSetProperty.

environ un mois ago | 1 download |

Answered
how to solve 'Error using | Matrix dimensions must agree. ' ?
Maybe this line: while (Lia2_One_Three ~= zeros(length(Lia2_One_Three),1) | Lia2_Two_Three ~= zeros(length(Lia2_Two_Three),1)...

environ un mois ago | 0

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Answered
Print from C file into Command window via MexFile
"However I would like to print directly from the c-file to Matlab Command Window. Is that possible?" Yes, that is what mexPrint...

environ un mois ago | 1

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Answered
could anyone help me to solve the issue with respect to the code
The syntax of a for-loop is: for k=1:5 % your code here end

environ un mois ago | 0

Answered
Subtracting matrices using a for loop
diff(your_data,1,3)

environ un mois ago | 0

Answered
How can I see the filter function implementation code at MATLAB?
In general, if the function has an associated .m file then TMW is willing to show you that much. Also there may be information ...

environ un mois ago | 1

Answered
If else problem for year
All of those if-elseif blocks make the code difficult to read, and difficult to debug as well. I would advise against that appr...

environ un mois ago | 0

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Answered
Please how can I store all my matrix?
Maybe use a cell array: channel{i} = [importdata(location)]; Then at the end you can work with the individual matrices as chan...

environ un mois ago | 1

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Answered
Fast Elementwise Matrix-Multiplications
The element-wise times operation in MATLAB is already multi-threaded. You are not going to beat it by writing your own low leve...

environ un mois ago | 0

Answered
Defining velocity over particular time frame
You don't need a loop for the velocity. Assuming I understand that you want the velocity to be linear, you just need a vector t...

environ un mois ago | 0

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Answered
Converting C++ bits packed int** to MATLAB unisgned char mxArray using mex?
Some issues: 1) The signature of mxCreateNumericArray according to the doc is: mxArray *mxCreateNumericArray(mwSize ndim, cons...

environ un mois ago | 0

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Answered
Find an optimal solution for a linear system with two inequations
The way you have this problem posed, and assuming by "binary" you mean integer, it can be solved by simple inspection. The max ...

environ un mois ago | 0

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