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James Tursa


Last seen: 1 giorno ago Active 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
Use trapezoidal method to find the deflection at each measurement point.
Sounds like you want the cumtrapz( ) function. If the assignment requires you to use loops, just code up the formula found in th...

circa 14 ore ago | 0

Answered
How to convert decimals to Ascii characters?
Your table isn't ASCII encoding of characters, so you can't use simple functions such as double( ) etc. You are probably going t...

circa 16 ore ago | 1

Answered
Trapezoidal numerical integration using for loops
See the Trapezoidal Method section here for the fomula: https://www.mathworks.com/help/matlab/ref/trapz.html?searchHighlight=tr...

1 giorno ago | 0

Answered
a)Extract the data from the two columns into separate arrays named time and distance. b) Determine the velocity and acceleration of the rocket. Use a FOR loop or as many as d
Hints for using a difference method: Velocity = Position / Time Acceleration = Velocity / Time To get the delta values, just...

1 giorno ago | 0

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Answered
Change of position of velocity vectors and time interval between the change
Looks like an orbit problem. Around the Earth, I presume? You will not be using the Symbolic Toolbox for this assignment. You w...

4 giorni ago | 1

Answered
Any comment to speed up the speed of caculation of symbolic loops having Legendre polynomials?
The Symbolic Toolbox is going to be slower than IEEE floating point ... that's just something you have to accept. And if you nee...

8 giorni ago | 1

Answered
Formula for norm(x)
This question appears to be a follow-up to this post: https://www.mathworks.com/matlabcentral/answers/1809695-what-exactly-norm...

9 giorni ago | 0

| accepted

Answered
what exactly norm(x) function do?
The equivalent function to norm( ) for a complex column vector x is sqrt(x' * x) where x' is the complex conjugate transpose. ...

10 giorni ago | 1

| accepted

Answered
Why am I receiving Not enough input arguments?
The error seems pretty clear, you are calling func( ) without enough input arguments. The func( ) signature has six inputs: fun...

10 giorni ago | 1

| accepted

Answered
I have some coupled nonlinear ordinary differential equations. Three equations have three 2nd order derivative coupled together. Can someone tell me how I can get the response
Another related approach is to isolate all the 2nd derivatives on the LHS and put everything else on the RHS. Then pick off the ...

10 giorni ago | 0

Answered
how to use exp for this problem
You need to use the * operator to multiply in the denominator. E.g., w=exp(-(i-Un)^2/(2*sd^2)) If i is not a variable defined ...

10 giorni ago | 0

Answered
Multiple Outputs of a function into a single vector
You could modify f( ) to return a vector. Or if you didn't want to modify f( ) you could create a helper function that does this...

11 giorni ago | 1

Answered
dynamic matrix with changing variable name in for loop
Do not dynamically name variables. This is bad programming practice and will leave you with hard-to-use variables downstream in ...

11 giorni ago | 0

Answered
ODE solver for restricted 3 body problem
In this line: dydt(2) = y(1) + 2 * dydt(3) - mu_p * ((y(1) + mu)/D1) - mu * ((y(1) - mu)/D2); you use dydt(3) before you set i...

12 giorni ago | 0

| accepted

Answered
Write a function file that computes the roots of a quadratic using the form for x+ and x−1 that are least susceptible to cancellation error.
Is this the type of formulae you are being asked to code? https://people.csail.mit.edu/bkph/articles/Quadratics.pdf https://st...

12 giorni ago | 0

Answered
How to get the same number of char as number of decimals using num2str?
You might look into using the fix( ) function to isolate the fractional part of your number and then work with that directly.

15 giorni ago | 0

Answered
matrix to struct do not match
You should really show us all of the actual code in question, not just a wordy description of the code. A better description and...

16 giorni ago | 0

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Answered
Assign elements in multidimensional struct to 2D array
You can use the vercat( ) function to force the comma-separated-list generated by C.pts to stack vertically: for ii=1:5, C(ii)....

17 giorni ago | 1

| accepted

Answered
Singular Value Decomposition calculation of a matrix
By changing the order of the rows you have changed the order of operations inside svd( ). The two answers are essentially the sa...

18 giorni ago | 1

| accepted

Answered
Issue with N body problem using ode45
You need to rethink your problem statement and initial conditions. The initial positions can't possibly be in the neighborhood o...

24 giorni ago | 0

Answered
What is the best function of the following shape?
There are lots of functions that could fit this general shape. E.g., sin(x), or more generally A*sin(B*x+C) depending on width a...

25 giorni ago | 0

Answered
Rotate an image 180 degrees without library functions
Hint: Take a small example, rotate it 180 degrees, and see where the elements end up. Then consider how you might get that resul...

26 giorni ago | 0

Answered
How to rearrange columns in a MATRIX?
One way: [X(:,1:2);X(:,3:4)]

27 giorni ago | 0

Answered
How to calculate the mean value of the non vero value in a vector?
Another way that doesn't require any data copying: M = [0.7,0.3,0]; sum(M)/nnz(M) Be aware that if there are no non-zero elem...

29 giorni ago | 1

Answered
Adding value from structure into a vector after each iteration of a for loop.
The reason you are getting a 2x8x2 answer is because you start with a 1x8 vector but then assign spots outside of those limits i...

circa un mese ago | 0

Answered
parallel sum different from serial sum
Bruno and IA have already given the reasons for this discrepancy. I would simply add that even though you are adding integers an...

circa un mese ago | 2

Answered
how to multiply quaternion wth 1x3 vector
Use BECI as the "vector" part of a quaternion and put a 0 in the "scalar" part, and use that new quaternion in the multiply. Sin...

circa un mese ago | 1

Answered
I want to convert vector into matrix with all possible combinations
I think John D'Errico answered this some time ago, or a question very much like this. But I can't find his post at the moment. I...

circa un mese ago | 0

Answered
Can compare between vector and array
Does this do what you want? Finds the row numbers in A that match x. find(all(A==x,2))

circa un mese ago | 0

| accepted

Answered
Modify off diagonal elements of Matrix without looping
You could use logical indexing to get at the off-diagonal elements. E.g., A(~eye(size(A))) = skalar;

circa un mese ago | 0

| accepted

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