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James Tursa


2,976 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
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

3 hours 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...

3 hours 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 ...

2 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 ...

2 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...

2 days ago | 0

Submitted


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

2 days ago | 9 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...

3 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...

3 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(:)];

3 days ago | 0

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Submitted


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

3 days ago | 7 downloads |

Submitted


SHAREDCHILD creates a shared data copy of contiguous subset
SHAREDCHILD creates a shared data copy of a contiguous subsection of an existing variable

3 days ago | 5 downloads |

Answered
mxCreateNumericArray error: cannot convert 'int*' to 'const size_t* {aka const long long unsigned int*}' for argument '2' to 'mxArray*
Simply replace this int* dims = new int[par->ndim]; with this mwSize* dims = new mwSize[par->ndim];

7 days ago | 1

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Answered
How do I implement bsxfun column-wise?
C = arrayfun(@(i)func(A(:,i),B(i)),1:size(A,2)) This just hides the loops behind arrayfun ... it doesn't eliminate them.

7 days ago | 1

Answered
how to replace a column in a matrix
Instead of replacing all of the columns of A, use a different variable for the result. E.g., a cell array named C. So instead o...

8 days ago | 0

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Answered
Function Return only one value
Call it with two requested outputs: [X,Y] = MyEKFFun(31,24,18,330,364,379,1,1.1,1.3,2) Since you were calling it with no reque...

8 days ago | 3

Answered
any easier way to find cell by string
Assuming the strings all start with 'test', e.g. find(cellfun(@(C)C(end)=='a',A))

8 days ago | 0

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Answered
cant workout why vectors aren't the same length
If you pass zeros( ) only one argument, it creates a square 2D matrix, not a vector. So give it two arguments to make your resul...

8 days ago | 0

Answered
Question about array alternating between positive and negative
Seems like there should be a shorter way, but assuming you are looking for all 0 crossings and not just the positive to negative...

9 days ago | 0

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Answered
Can you compile a code including linprog function?
If you look here, linprog is not one of the Coder supported functions: https://www.mathworks.com/help/coder/ug/functions-suppor...

9 days ago | 0

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Answered
Writing a MATLAB script for equations
E.g., put these lines in a file with a .m extension: lambda = input('Input a value for lambda: '); mtbf = 1 ./ lambda; Are yo...

9 days ago | 1

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Answered
Lapacke in level-2 C S-function
According to the interface listed here and the link you list above: http://www.netlib.no/netlib/lapack/double/dpotrs.f The n, ...

9 days ago | 0

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Answered
Index Exceeds Array Bounds
Normally I would have expected to see code that sets the next values of x and y, but I don't see it. I.e., I am looking for line...

9 days ago | 0

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Answered
Finding remaining numbers in logical indexing?
E.g., find1 = length<1; : find2 = (length < 3) & (max_width_head > mean_width_neck*2); : find3 = max_width_head>=me...

9 days ago | 0

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Answered
How to use mxCreateNumericArray
This line is incorrect (wrong function and signature): plhs[0] = mxCreateNumericArray(xynum,1,mxINT16_CLASS); /*Creates a ma...

10 days ago | 0

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Answered
Why is my if statement breaking when condition is not met?
The == operator is an element-wise operator. You need to use a string comparison function for this. E.g., if( strcmpi(verbose...

10 days ago | 0

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Answered
Multidimensional arrays do not work in mex functions?
You can't use multi-level [ ][ ]... syntax with simple pointers. E.g., look at these lines: void matsum(double *dphidt, double ...

10 days ago | 0

Answered
An efficient (quick) way of entering complex data into Matlab workspace.
Assuming you are using R2018a or later, you might try this FEX submission which can reinterpret real variables as interleaved co...

10 days ago | 0

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Answered
How to get direction for 3d angles between 2 vectors
You will need to define in your code which direction is the clockwise and which is counterclockwise. You can do that by definin...

13 days ago | 1

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Answered
How to code this problem?
E.g., syms x A = [1 2 4 5]; n = numel(A); P = prod(x-A); X = cell(n,1); for k=1:n X{k} = P / (x-A(k)); end This giv...

13 days ago | 0

Answered
ODE45 generates undesired matrix of NaN entries
This is often an initial condition issue with the specific DE's involved. In your code, you have icond(2) = 0 icond(3) = ((F/...

13 days ago | 0

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