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James Tursa


Last seen: 1 day ago
3,585 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
Fast conversion of 2 matrices to 1 complex matrix
See this FEX submission for reading and writing interleaved complex data in R2018a or later without extra data copies: https://...

6 days ago | 0

Answered
How to replace leading zeroes by spaces with regexprep
One way: fun = @(x)sprintf(['%' num2str(numel(x)) 'd'],str2double(x)); d = cellfun(fun,a,'uni',false); e = cellfun(fun,b,'uni...

6 days ago | 0

Answered
trimming matrix arrays arranged within cell arrays
It is not clear whether you want the rows or columns trimmed. Maybe one of these is what you want? TrimmedArray = cellfun(@(x) ...

6 days ago | 0

Answered
Runge-Kutta 4th order function error (Matrix dimensions must agree)
Your RK_4 function is not set up to handle vector equations ... it is only set up to handle scalar equations. Also you are not ...

6 days ago | 0

Answered
How to pass arguments by reference from Matlab?
doc loadlibrary Create a C header file that gives prototypes for the Fortran subroutines and treat the Fortran arguments as poi...

11 days ago | 0

Answered
how to create an array of all permutations
If you want all of them in an array (which might be too large if the number of digits is too large), you can use n = number of ...

12 days ago | 0

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Answered
Trying to do calculations for density
Why do you have these lines in your function: P_t=4; P_s=3; H=25; Aren't these variable supposed to be input arguments? See...

13 days ago | 0

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Submitted


freadcomplex and fwritecomplex
Mex routines that read and write interleaved complex data files for MATLAB R2018a or later without extra data copy.

13 days ago | 3 downloads |

Answered
efficient ways to read and write complex valued data
A mex routine to accomplish this that doesn't use any hacks can be found here: https://www.mathworks.com/matlabcentral/fileexch...

14 days ago | 0

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Answered
efficient ways to read and write complex valued data
This may not apply to you, but if you have R2018a or later you can just fread( ) into a real variable directly the interleaved d...

14 days ago | 0

Answered
Changing contents of Cell Array mex files
When you mxDestroyArray a cell array or struct array, it does a deep destroy. Meaning all of the cell array or struct array ele...

18 days ago | 0

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Answered
solution with the Runge-Kutta method HELPP
This is clearly a homework/exam question, so I will only offer hints. The code you have posted is for a single scalar different...

19 days ago | 0

Answered
How could I use MATLAB to solve for x with this equation, 0=a*x^(3)+b*x^(-1)+c.
Just use the roots( ) function. If you have a negative integer power of x in the expression such as x^(-n), then multiply every...

20 days ago | 0

Answered
reshape loop resulted cell array
result = cell2mat(c1(:))';

25 days ago | 0

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Answered
Matrix with nested for loops
You don't need loops for this. E.g., p = the probability result = rand(20,20) < p; % your matrix of 0's and 1's

25 days ago | 0

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Answered
Bit xor of two binary strings and conversion into decimal
The xor part as a logical vector result result = str1 ~= str2; Or if you wanted it as char: str3 = char((str1 ~= str2) + '0')...

25 days ago | 0

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Answered
Function 'quatrotate' not supported for code generation.
You can always write your own. Just code up the matrix multiply at the bottom of the doc page: https://www.mathworks.com/help/...

25 days ago | 1

Answered
Reshaping a complex 3D array into 1D, and back
I suspect the problem may be that you originally put the data into rows of a matrix. This separates the elements in memory. I....

26 days ago | 0

Answered
Problem with function handle
f by itself is just a function handle, not the function handle evaluated for any input. You need to give f an input. E.g., b=...

26 days ago | 1

| accepted

Answered
How can I find all possible combinations of rows from two separate arrays?
E.g., For arbitrary values in A and B, doesn't have to be B = -A n = size(A,1); C = repmat({A},2^n,1); mask = dec2bin((0:(2^n...

26 days ago | 0

Answered
Velocity,Acceleration,Angle
This is a dynamics class. Dynamics involves derivatives. How can you be in a dynamics class without knowing calculus and how t...

27 days ago | 1

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Answered
Randi(imax,m,n)
The point is that once the eps of the max value is greater than 1, you cannot represent contiguous sets of integer values in dou...

27 days ago | 2

Answered
How this code works and why for? What action does this code take?
You could look here: https://en.wikipedia.org/wiki/Bubble_sort

27 days ago | 1

Answered
Creating all possible combination of a letter/string
One way to create a matrix of these character strings: dem_a='ABC'; % assume starting string is all upper n = numel(dem_a); r...

27 days ago | 0

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Answered
Implementation of a matrix
You haven't told us what x and e are, but assuming x is a vector and e is a scalar, simply this: result = cos( (1:n) .* x(:) * ...

28 days ago | 4

| accepted

Answered
Array indices must be positive integers or logical values.
n = 0 and then you use it as an index: n=0; for i=n:1:tam-1 if xi(n)*xi(n+1)<0 You can't have a 0 index. Also, min is t...

1 month ago | 0

Answered
Formatting floating and integer signed numbers
sprintf("%0.2f%+0.2f",a,b) Having the + inside the %format stuff forces the sign to print.

1 month ago | 0

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Answered
For-loop in MATLAB
You should not modify the index variable i inside the loop: for i = 1:length(Corr_vector) : i=i+44; % this is ba...

1 month ago | 0

Answered
Finding All Combinations of Elements in a Vector
N = 6; result = dec2bin((0:(2^N-1))') - '0'; Then the various vectors you want are the rows of result. Or, if you really want...

1 month ago | 1

| accepted

Answered
About floating point format
The 64-bit floating point format is IEEE double: https://en.wikipedia.org/wiki/Double-precision_floating-point_format The 32-b...

1 month ago | 0

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