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James Tursa


Last seen: Today 2007 年からアクティブ

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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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質問


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...

11日 前 | 2 件の回答 | 0

2

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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...

14日 前 | 0

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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...

19日 前 | 1

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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...

20日 前 | 0

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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...

27日 前 | 1

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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...

約1ヶ月 前 | 1

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

約1ヶ月 前 | 0

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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...

約1ヶ月 前 | 0

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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).'

約1ヶ月 前 | 0

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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...

約1ヶ月 前 | 0

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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 ...

約1ヶ月 前 | 0

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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

約2ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 1

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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ヶ月 前 | 1

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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 ...

2ヶ月 前 | 2

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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 = ...

2ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 1

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質問


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ヶ月 前 | 1 件の回答 | 1

1

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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ヶ月 前 | 0

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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ヶ月 前 | 2

送信済み


SAREK - Sparse Analyzer Real Et Komplex
The SAREK function analyzes a sparse matrix for integrity. Useful especially for checking sparse matrices built by 3rd party s/w...

4ヶ月 前 | ダウンロード 5 件 |

回答済み
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ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 0

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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ヶ月 前 | 0

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