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James Tursa


Last seen: Today Con actividad desde 2007

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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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Respondida
Matlab got this wrong: Limit as n goes to infinity: (1+(i/n))^(n^2). Matlab says it's exp(2), which is wrong. Pls confirm.
I have been looking at this for a couple of days now and have finally convinced myself that this limit doesn't exist and MATLAB ...

3 días hace | 0

Pregunta


Duration type doesn't preserve seconds accuracy
I've been working on some time conversion routines and ran into an issue I didn't expect. Basically, the duration type doesn't p...

15 días hace | 2 respuestas | 0

2

respuestas

Respondida
Rank value matrix from 3d Matrix
Might be easier to permute first so that your 2D matrices are in the first two spots. Then simply use sort() to get the rank ind...

18 días hace | 0

Respondida
Error with matrix calculation
We don't have all the variables necessary to run your code, but guessing that maybe you need element-wise divide instead of matr...

23 días hace | 1

Respondida
Unable to resolve the name 'half.typecast'
half is an opaque data type in MATLAB, not a regular numeric type like double and single. I tried to get TMW to change this to a...

24 días hace | 0

| aceptada

Respondida
What does it mean "/Multiple" after variable name in *.mat file?
If the file is written by a 3rd party tool, it is probably written in uncompressed format. In that case, and if the /Multiple is...

30 días hace | 1

| aceptada

Respondida
Having issues writing matrix to a binary file.
@Rikin You forgot to read in the sizes. You only read in the double data. The two int32 variables at the front obviously were pa...

alrededor de 1 mes hace | 1

Respondida
How to write a matrix with elements 10,30,10
Use brackets M2 = [10,30,10]

alrededor de 1 mes hace | 0

Respondida
an ode with arguements
Create a new function handle with your extra stuff. E.g., mufunT = @(eta,f) mufun(eta,f,guessT) [eta, f] = ode45(mufunT, [lins...

alrededor de 2 meses hace | 0

Respondida
Column to matix In matlab
Depends on how your data is currently stored. Suppose the data is currently in a vector v. Then matrix = reshape(v,50,10).'

alrededor de 2 meses hace | 0

Respondida
How do I process a string class in a mex function?
Strings are opaque objects (like classdef) and there are no API functions to get pointer access to the data areas. I am unaware...

alrededor de 2 meses hace | 0

Respondida
How to convert dates into Julian dates?
Based on your comment that you are expecting numbers in the range of 273,287,298, etc., if what you are after is actually "day ...

alrededor de 2 meses hace | 0

Respondida
How to create for loop for calculating euclidean distance of a matrix?
Does pdist() do what you want: https://www.mathworks.com/help/stats/pdist.html?s_tid=doc_ta

alrededor de 2 meses hace | 0

Respondida
converting 3d matrix into a cell array
x = rand(1001,259,259); result = arrayfun(@(k)squeeze(x(k,:,:)),1:size(x,1),'uni',false); size(result) size(result{1}) But, ...

2 meses hace | 0

Respondida
How to implement the Central Difference method integrator for a two body problem?
You have: altitude tangential velocity If you just want the orbital period, you can calculate as follows using the Vis-Viva e...

2 meses hace | 0

Respondida
Can multiple versions of MATLAB be installed on the same Windows PC using the same license number for code compatibility?"
Multiple MATLAB versions can be installed on the same machine as long as your license permits it. Both can even be run simultan...

2 meses hace | 0

Respondida
How to calculate the angle between two 3D vectors?
See a discussion here (includes a tiny angle example): https://www.mathworks.com/matlabcentral/answers/101590-how-can-i-determi...

2 meses hace | 1

Respondida
Double precision: Why does fprintf print "extra" wrong non zero digits?
The "extra" digits that look incorrect to you are simply the result of doing an exact conversion of the actual floating point bi...

2 meses hace | 1

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Respondida
What does MATLAB actually do when switching precisions?
When converting from IEEE single to double, the sign bit is retained, the exponent bits are adjusted to match the same exponent ...

3 meses hace | 2

Respondida
I want to solve ODE for a complex systems in a rk4 method
Just turn all the y( ) stuff into row or column vectors. E.g., suppose we use column vectors, then something like this ... y = ...

3 meses hace | 0

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Respondida
quat2angle / atan2 strange quadrant change when calculating angle
You don't show us your code, but in general I would note that angle changes like this are sometimes the result of whole quaterni...

3 meses hace | 0

Respondida
Active rotation with quaternions: from initial orientation given with Euler angles get the new orientation after an active rotation described by the qr quaternion.
Yes, for your convention q' = q * qr is mathematically correct. But note that this formula only works for certain quaternion co...

3 meses hace | 1

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Pregunta


Conjugate of Symbolic Root doesn't change anything
Reference question first asked here: https://stackoverflow.com/questions/78010011/matlab-bug-with-root-and-conj Basically, the...

3 meses hace | 1 respuesta | 1

1

respuesta

Respondida
sparse matrix entries are not displayed correctly
I finally finished my sparse matrix integrity checker. You can find it in the FEX under the name SAREK (I think you will be able...

4 meses hace | 0

Respondida
the tranpose of transpose doed not equals the original matrix
I finally finished my sparse matrix integrity checker. You can find it in the FEX under the name SAREK (I think you will be able...

4 meses hace | 2

Respondida
Help with state representation of my 3-mass 2-spring system
The k terms in the equations above appear to be non-linear. Your A matrix doesn't account for the cubic parts.

4 meses hace | 0

Respondida
Calculate angles correctly between two vectors using the dot product.
Also see this related link for a robust method using atan2 that can recover small angles: https://www.mathworks.com/matlabcentr...

5 meses hace | 0

Respondida
How can I make memory persistent between calls to a MEX-file in MATLAB?
So, the accepted answer has bugs. Namely: They don't include the header for memcpy They don't check the input argument properl...

5 meses hace | 0

Respondida
Index in position 1 exceeds array bounds (must not exceed 8).
Here is how to debug these types of errors: Type the following at the command prompt: dbstop if error Then run your code. Whe...

5 meses hace | 0

Respondida
matlab mex in-place editing via "mxUnshareArray" or similar functionality
So, MATLAB has never officially supported modifying input variables in-place in a mex routine. There are potential side effects ...

5 meses hace | 0

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