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James Tursa


3,185 2007 年以降の合計貢献数

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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Matrix multiplication using multicore
The matrix multiply operator * calls a highy optimized compiled BLAS library to do this calculation. The BLAS library is alread...

約4時間 前 | 0

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How to write a function
MATLAB is case sensitive, Output is not the same variable as output. Also, you need to square the Top value, and depending on w...

1日 前 | 0

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How to efficiently do matrix multiplication for 2 specific dimensions of the tensor?
Some FEX options that might work for you (some require an installed C compiler): https://www.mathworks.com/matlabcentral/fileex...

2日 前 | 0

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ode45 given a systems of equations help
First, look over the examples in the ode45 doc. Then figure out the order of your system, and that will tell you the size of yo...

3日 前 | 0

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Create an Array of vectors within a for loop
If you want to store the column vectors, you could use cell arrays. E.g., k = 1; for j=0:100:5000; : [PXX{k},F{k...

3日 前 | 0

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ODE matlab, handling variables
You can't do this if the derivative yd depends on k. The ode solvers need to have consistency when calling the derivative funct...

3日 前 | 0

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two body problem using ode45
The RK methods don't match up well with the orbit DE problem because the integration errors tend to be systematic (e.g., always ...

3日 前 | 1

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Duffing Oscillator issue. "Keep getting Unable to perform assignment because the left and right sides have a different number of elements."
t is a vector, so your cos(omega*t) is a vector. You need to use cos(omega*t(n)) there.

4日 前 | 0

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double integration of acceleration data with offset
You put a constant offset into the acceleration, not the position. The result of double integrating a constant is going to be a ...

4日 前 | 0

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Need help verifying code for Euler MEthod, RK2 and RK4
Your biggest problem is that you don't have the differential equations coded correctly. And the main cause of that is because y...

4日 前 | 0

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Numerically Integrating the differential equation below?
You've got two 2nd order DE's, so that means you have a 4th order system (2x2=4) and thus your state vector will contain four el...

4日 前 | 0

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Generate all possible combinations for the column vectors of a matrix
E.g., >> B = [1;2]; >> n = 3; >> Bcell = arrayfun(@(k)B,1:n,'uni',false); >> C = allcomb(Bcell{:}) Warning: NARGCHK will be...

4日 前 | 1

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Removing single quotations from a character array
Your answer does not include the bounding single quotation marks ... that is just a display artifact for how MATLAB prints chara...

5日 前 | 0

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Help, I don't understand why the output multiplies everything by 1.0e+03
That's just the default way that MATLAB displays the numbers, rather that tacking e+03 to each number individually. You could u...

7日 前 | 0

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Error trying to solve 2 Second ODE
Just looking at func.m, it appears you pass in a 4-element x vector, but you only return a 2-element a vector. You need to retu...

7日 前 | 0

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vpa doesn't seem to work
You are passing a double into vpa( ), so your precision is lost before you even call it. You could pass in a string instead: n ...

9日 前 | 1

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A function to find prime number
Your function doesn't return anything, so when you try to use its output you get an error. Change this: function isPrime(numbe...

9日 前 | 0

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Rolling all six numbers on a six sided die
This: v = zeros(1,NToys); NRolls = 0; needs to be inside your Trial loop so that it resets for each trial. A simpler way to ...

10日 前 | 0

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Need help Euler Method
The fundamental thing you are doing wrong is that you don't have the proper size state vector. For a 1st order equation, the st...

10日 前 | 0

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How can I add values of an array as an input into the ode45 function ?
What is the size of I? What is the DE you are solving? Maybe just dropping the (t) will work: dydt= (-I/(3600*Q)); Or maybe ...

10日 前 | 0

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double differentiation and double integration of sine wave
"... when differentiating my position to get velocity and acclereation i did work out all three of them by hand, quite sure it i...

10日 前 | 0

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Comparison of two Vektors with different size to find variables
E.g., x = ismember(b(:,1:2),a(:,1:2),'rows'); c = b(x,:); Depending on how the times were constructed, you might need to use ...

10日 前 | 0

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How to transfer parameter between C and fortran
Maybe the Fortran compiler settings are compiling the default integer as 8-byte integers. Try forcing the Fortran to use 4-byte ...

10日 前 | 0

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How to sort a matrix in a random order
E.g., >> x = reshape(1:24,4,6) x = 1 5 9 13 17 21 2 6 10 14 18 22 3 7 ...

11日 前 | 0

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can someone help me to solve this error (This statement is not inside any function. (It follows the END that terminates the definition of the function "RK4".)
Looks like your plot( etc ) and legend( etc ) lines are stuck inbetween two functions. Did you intend them to be inside a scrip...

11日 前 | 0

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making array in for loop
Maybe prior to the loop define Alignment as a cell array to hold your results: Alignment = cell(10000,1);

15日 前 | 0

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Why is my function generating a vector? Please help?
A uniform random number between a and b is: u = a + rand*(b-a) Generate two of these with a = -0.05 and b = 0.05 and then do t...

16日 前 | 0

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Can someone explain the concept of B= null(A) in simple words?
The columns of B form basis vectors for the "null space" of A. Any linear combination of the B columns, when multiplied by A, w...

16日 前 | 1

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Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 5-by-1.
Looks like Cd and rho are vectors. So the result of those calculations on the right hand side will be vectors. But you are tryin...

16日 前 | 0

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What can I use instead of VPA?
See the following FEX submissions by John D'Errico: https://www.mathworks.com/matlabcentral/fileexchange/36534-hpf-a-big-decima...

17日 前 | 1

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