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James Tursa


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3 740 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
plotting complex exponential function
E.g., maybe this is what you need y = 1*exp( -i20 *pi * t ) + 4*exp( i20 * pi * t ); plot(t,y); Although it is not clear what...

ungefär 13 timmar ago | 0

Answered
Coding Crowell's Method for Orbiting Bodies
I don't have the patience to go through all of your dim and dimc logic. It would seem to be much easier to code and debug if yo...

ungefär 14 timmar ago | 0

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Answered
Plot the acceleration with ODE45
You find acceleration by taking the x solution from ode45( ) and feeding that back into your derivative function vdp1( ). Since...

ungefär 15 timmar ago | 0

Answered
Multiplying by inverse of a matrix
You are essentially "dividing" by the X'*X quantity, so that is what needs to appear on the "bottom" of the slash. E.g., >> alp...

2 dagar ago | 1

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Answered
"Matrix Dimensions must agree"
t is used to build r, but it is not the same length as phi.

4 dagar ago | 1

| accepted

Answered
How to create a periodic function?
Not sure what you mean by "repeated at [2,10]". Maybe this: y = mod(x,2); ix = y > 1; y(ix) = 2 - y(ix);

5 dagar ago | 0

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Answered
How do i use output of one function as input to the other ?
You can do this at the point where you are calling the function neg. E.g., z = neg(pos(x,y),q);

5 dagar ago | 0

Answered
Index in position 1 is invalid. Array indices must be positive integers or logical values.
When i=m in your loop you try to access kernel(m-m,n-j) which is kernel(0,m-j), and 0 is an invalid index. Similar problems wit...

5 dagar ago | 0

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Answered
Solve a differential equation system with 4th order Runge-Kutta method with three equations
Not sure if you actually use t in your derivative functions, but you are missing that input from your j1, k1, and l1 code: ...

5 dagar ago | 0

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Answered
sum of cubes question
This homework question is poorly written: It seems like the intent of the n is to use it as the upper limit of the for-loop, bu...

5 dagar ago | 1

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Answered
Calling a function from another function
my_first_function1( ) doesn't return any value to the caller. To return a value you use this syntax: function absx = my_first_...

6 dagar ago | 1

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Answered
Numerical integration of the differential equation of motion of the two body problem
Your biggest problem is that you don't carry enough states in your derivative function. Your ODE is a 3D 2nd order equation, so...

6 dagar ago | 0

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Answered
How to swap multiple rows of a matrix at a time
A = your matrix A([1:63,142:202],:) = A([142:202,1:63],:);

7 dagar ago | 0

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Answered
Probability of binary sequence with Monte Carlo
First point is that probability of stopping at n=3 is not 2/6, it is (3/4)*(2/6) because you have to include the probablility th...

9 dagar ago | 1

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Answered
Problem at +/- 180 degrees in orientation estimation from IMU data
You can try the unwrap( ) function: https://www.mathworks.com/help/matlab/ref/unwrap.html

9 dagar ago | 0

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Answered
Help with secant method
You might look here which even includes example code: https://en.wikipedia.org/wiki/Secant_method

10 dagar ago | 0

Answered
How do I add an integer to every or any nth row
A(k,:) is the k'th row of A A(:,k) is the k'th column of A A([k m p],:) is the sub-matrix formed from the k'th, m'th, and p'th...

10 dagar ago | 1

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Answered
First and last occurrence of an element in an array
So the description of the problem doesn't say anything about consecutive values, so the code you have for that should be elimina...

10 dagar ago | 0

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Answered
Parse error at ']'
Looks like you just need commas instead of periods. E.g., [r,i,v,dr,di,dv]

11 dagar ago | 0

Answered
Simple Blackjack Simulation in MATLAB
A few things ... Seems like you should have this: deck = repmat([1,2,3,4,5,6,7,8,9,10,10,10,10],1,8); % two decks worth of car...

11 dagar ago | 0

Answered
Can not convert USHORT MAX to ufix16_Sp01
If you have a slope scaling of 0.01 and a bias of 0, doesn't that mean the max value is 65535*0.01 = 655.35?

11 dagar ago | 0

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Answered
Using ODE45 for coupled equations
General procedure: Define a variable, let's call it y to match the doc, that will be your state vector. Each element of y corr...

11 dagar ago | 0

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Answered
please help with work
Use the input( ) function to get the user input. Use the optional 's' argument to get the input as a char string. I'm assuming...

11 dagar ago | 0

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How to get Matlab Version at Mex Compilation Time?
My MATLAB version code works for me in R2020a: >> mex matlab_version_test.c Building with 'Microsoft Visual C++ 2015 (C)'. ME...

11 dagar ago | 0

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Answered
Is there a way to use symbolic functions in ode45
Convert it to a function handle so that it can be used with numeric inputs. E.g., >> syms x >> f(x) = sqrt(x) + 2 f(x) = x^...

11 dagar ago | 1

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Answered
how to write matlab code for physics problem?
You do not explicitly state that acceleration is constant, but I assume that is the case. The equations then are simply vf = v...

11 dagar ago | 0

Answered
I need help for calculating mortgage for a homework problem
OK, so ask yourself what has to happen every month? You get charged interest and you make a payment, right? And you are told t...

12 dagar ago | 0

Answered
forward euler for a system of equations
I'm assuming this for j=1:t1:dt was meant to be something like this for j=1:t1/dt

12 dagar ago | 0

Answered
Splitting a vector into a matrix
result = [x(1:2:end) x(2:2:end)]; or result = reshape(x,2,[]).';

12 dagar ago | 1

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Answered
Mex file c. Getting different results from matlab
MATLAB stores matrices in column order. E.g., if A is a 2x3 matrix, and p is a pointer to the data area of A in a mex routine, ...

12 dagar ago | 0

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