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James Tursa


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3.538 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
arrayfun syntax and use with scalar input
To use a scalar you could use this syntax: a=[1 2;3 4]; b=2; c=arrayfun(@(x)x+b,a); The function handle would pi...

4 dagen ago | 0

| accepted

Answered
Access violation detected - MEX
If it worked fine on 32-bit, then of course the most likely problem is you missed something in the integer or pointer size conve...

4 dagen ago | 0

Answered
how to plot a polynomial?
doc polyval doc colon doc plots doc roots

5 dagen ago | 0

Answered
Use of arrayfun but with passing a fixed variable to function handle?
matrix(:,3) = arrayfun(@(a,b)max(diff(spikeTimes(a:b))),start_temp,stop_temp);

7 dagen ago | 0

| accepted

Answered
howto organize an array into groups of n-Elements
Another way: x = 1:100; a = reshape (x,5,20); aa = [a;a]; v = cell(1,5); for k=1:5 v{k} = aa(k:k+4,:); end Then the ...

8 dagen ago | 0

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Answered
using for loop with if
I'm guessing you want a newline at the end? fprintf(' Ik = %.f \n', abs (Ik))

9 dagen ago | 0

Answered
movements of the descent vehicle in the atmosphere of Earth
You have four differential equations involving four variables: V, theta, H, and L. You have to solve these simultaneously since...

9 dagen ago | 0

| accepted

Answered
Error: Matrix dimensions must agree & Error: Function called failed while converting my code to C
This line: mat = (z).^(0:n+1); uses implicit expansion. z is a column vector and (0:n+1) is a row vector, so the result is in...

9 dagen ago | 0

| accepted

Answered
Can somebody help me to modify this code?
In this Brot = q.B.(q^-1) and this B = (q^-1). Brot.q expression, the dot (.) is likely supposed to represent quaternion mul...

9 dagen ago | 0

Answered
How can I call a *.dll file on a Mac?
dll's are compiled object code specific to the machine type they are compiled for. Are you trying to load the same dll file on ...

9 dagen ago | 0

| accepted

Answered
Inefficiency in MEX function when passing data into output
I am not sure you have enough insight into how codegen is going to code the randi, bsxfun, times, and sum functions to get what ...

9 dagen ago | 1

Answered
Invalid Mex file: Undefined symbol: mxrErrMsgTxt
All of the mxGetErrMsg references have been commented out in your posted code, so that is not the problem. I would guess that y...

10 dagen ago | 0

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Answered
I have a C function created using Compiler CDK and it's returning a large array but it's MxArray** type. How do I access all the data retunred to the calling C function?
A function signature like that typically means that the mlfMPrime_CA_P( ) function is creating an mxArray and then returning the...

10 dagen ago | 0

Answered
Why is 'size_t' in external C library interpreted wrong?
I am unaware of MATLAB treating size_t differently, but there is a potential error in your code snippet: int foo(size_t sz, uin...

10 dagen ago | 0

Answered
How can I speed up an exponential function?
I'm not sure what the issue is since you seem to already know about logical indexing. E.g., test1 = your data x = test1 > 0.0...

11 dagen ago | 2

| accepted

Answered
Result of asind changed between R2016b and R2019b
This is a bit strange. I would have expected the later version to be better, but it appears to be worse: >> version -release ...

12 dagen ago | 0

Answered
could you help me with this explanation?
It's possible you just need to switch to element-wise operators. E.g., OverallEffectinevess = (MassFlowFunction.*ConvectionCoo...

13 dagen ago | 0

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Answered
Solving Coupled ODE's by ode45
Start with your example (assuming that dx/dy was supposed to be dx/dt as you had originally): dx/dt = 3*(dy/dt) + 4*x, dy/dt = ...

13 dagen ago | 1

Answered
How can convert binary Numerical Values to Strings?
E.g. >> b = rand(5)<.5 % generate some sample data b = 5×5 logical array 0 0 0 1 1 0 1 0 1 1 1...

13 dagen ago | 1

Submitted


IEEE 754r Half Precision floating point converter
Converts MATLAB or C variables to/from IEEE 754r Half Precision floating point bit pattern.

13 dagen ago | 16 downloads |

Answered
how do you program the file path when you do not know where the person will save the matlab file you send them?
If you don't want to write code to search multiple directories to find the files, your code is going to have to ask the user to ...

16 dagen ago | 0

Answered
how do I get only 1 variable passed through a function?
switch choice; case '1' fprintf('What is the circle''s radius?\n') r = input(' '); [C,E] = circu...

18 dagen ago | 0

Answered
How do I create a matrix with all binary combinations?
dec2bin(0:2^N-1) - '0' Note that this is only practical for relatively small values of N. Even moderatly large N can cause thi...

18 dagen ago | 1

Answered
Not getting expected results
I get the identity matrix with your code: >> phi = 0; >> psi = 0; >> theta = 0; >> R=[cosd(phi).*cosd(psi)-sind(phi)...

19 dagen ago | 1

Answered
Obtain specific dimension from multidimensional Arrays
Not really sure what you are asking, but if you only want to pick off some indexes from an arbitrary dimension, simply supply th...

19 dagen ago | 0

Answered
How to exit a while loop after a certain number of values have been saved to a matrix
The general form for while loops is typically some variation of these: while( condition ) % stuff that eventually alters t...

19 dagen ago | 0

Answered
Using an array as input argument of a function handle
c = num2cell(a); J_num = J(c{:});

19 dagen ago | 0

| accepted

Answered
How to find the average of monte carlo simulation
You could save the r's in a vector. E.g., r(i) = poissrnd(lambda); Or you could generate all of the r's at once without the lo...

20 dagen ago | 0

| accepted

Answered
error decimal aproximation, extra decimal
Welcome to the world of floating point arithmetic! See this link: https://www.mathworks.com/matlabcentral/answers/57444-faq-wh...

20 dagen ago | 0

Answered
For loop for multiple scenarios
E.g., for k=1:numel(h_max) % use h_max(k), a_max(k), and SM(k) in your code here end Or if they need to vary independent...

20 dagen ago | 0

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