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James Tursa


2,995 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
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 ...

2 days 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...

2 days 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...

3 days ago | 1

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...

5 days 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...

6 days 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...

8 days 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 ...

9 days ago | 0

Answered
How to formulate the random matrix between real interval?
See the second example in the rand doc here, and use your endpoints of 0.10 and 0.50 instead of the example endpoints of -5 and ...

9 days ago | 0

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Answered
Complex matrix inversion using LAPACK in MEX
I took your code and modified it to be a mex routine that takes a 2D double complex input (caution: no argument checking done!) ...

9 days ago | 0

Answered
how to reshape this matrix
result = reshape(A.',2,[]).'

15 days ago | 0

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Answered
Simulation of irrational numbers
The random number generators that come with MATLAB have very long periods. You can simply use them to form your ratio and it wi...

16 days ago | 0

Answered
Printing out the element values in a mxDouble array (C++ script in Matab)
%d is a decimal integer format for use with short, int, long, etc. This doesn't work with floating point. Try e.g. %f or %g inst...

16 days ago | 0

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Answered
Runge-Kutta function
Here is some code to get you started. It receives a string from the user for a derivative function of x and t and turns it into...

18 days ago | 1

Answered
for loop continued fraction
Yes, you can use the formula x(n) = 1 + 1/x(n-1) if you want to use a loop. Just start with x(1) = 1.

18 days ago | 0

Answered
How to sum up multiple vectors, element by element, to recieve one final value?
The numerator is just a simple dot product between two vectors, and the denominator is just a simple sum. Using the fact that a...

18 days ago | 1

Answered
Creating a 2D random walk
In this logic, you will never get to the y branches because one of the first two x branches will always be true: if p_x<0.6 ...

19 days ago | 0

Answered
Is Walter Roberson a real person, or is he some kind of Matlab AI robot?
Blade Runner 2019 ...

19 days ago | 1

Answered
single precision simulation of internal calculations
" Is there a way to set Matlab to perform all calculations (even internal) to single precision? " Not the way you are probably ...

19 days ago | 0

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Answered
How do i convert this for loop into a while loop?
This for loop: for i=1:n % stuff end is equivalent to this while loop: i = 1; while i <= n % stuff i = i + 1...

19 days ago | 1

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Answered
How can I vertically concatenate cells?
I don't have much of a clue what you really need, but maybe this will give you a start on the MATLAB cell array syntax (with the...

23 days ago | 0

Answered
Functions, Error check
From your description, it seems like you simply need to test for the number of characters. E.g., while numel(outstring) == 0

24 days ago | 0

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Answered
How to implement such function?
Basically, just replace f(x) with f. E.g., f = constant; : f = coeffVector(i) * cos(i*x) + f; You could also do this wit...

24 days ago | 0

Answered
How to from I(x) to permutation and from permutation to I(x)
E.g., >> Per Per = 0 1 2 3 0 2 3 1 0 3 1 2 3 2 0 1 ...

26 days ago | 0

Answered
case of two mappings
Not sure which one is first, but maybe one of these is what you want? >> mapping1 = [0 1 3 2] mapping1 = 0 1 3 ...

26 days ago | 0

Answered
what wrong about this error
The error message appears when you have a mismatch in the number of elements on the rhs and the number of elements on the lhs. E...

26 days ago | 0

Submitted


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

26 days ago | 10 downloads |

Answered
Why is subtracting different sized matrices not giving me an error? What is matlab calculating?
See documentation on "implicit expansion" https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-op...

27 days ago | 0

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Answered
store values from loop in an array
Typos in your code: for i=1:length(A) And change tableA to TableA (MATLAB is case sensitive). Or, you could get rid of the l...

27 days ago | 0

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Answered
Combination of X and Y vectors to get all possible positions on a Cartesian plane
[XX,YY] = ndgrid(X,Y); Z = [XX(:),YY(:)];

27 days ago | 0

| accepted

Submitted


C Mex MATLAB Version
Mex C code to determine MATLAB version at compile time and run time

27 days ago | 10 downloads |

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