James Tursa

Last seen: Today

3.730 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.

Contact

James Tursa's Badges

View details...

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_...

alrededor de 9 horas ago | 1

| accepted

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...

alrededor de 12 horas ago | 0

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],:);

1 día ago | 0

| accepted

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...

4 días ago | 1

| accepted

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

4 días ago | 0

| accepted

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

5 días 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...

5 días ago | 1

| accepted

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...

5 días ago | 0

| accepted

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

5 días 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...

5 días 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?

5 días ago | 0

| accepted

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...

6 días ago | 0

| accepted

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...

6 días ago | 0

Answered
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...

6 días ago | 0

| accepted

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^...

6 días ago | 1

| accepted

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...

6 días 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...

6 días 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

7 días ago | 0

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

7 días ago | 1

| accepted

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, ...

7 días ago | 0

| accepted

Answered
I don't know how to prove sin^2(x)+cos^2(x)=1
[cos(x),sin(x)] is defined to be a point on the unit circle, so by definition we have sin^2(x) + cos^2(x) = 1 always. This isn'...

7 días ago | 0

Answered
Using loops in matrix
So your latest post is a really good effort! A couple of things you are missing from the instructions: "create a new variable ...

7 días ago | 1

Answered
How do I use function for a function which has a matrix with variable index?
You don't have a branch for the AR>Max case. If you hit that condition, the output variables will not be assigned. Also, ContA...

8 días ago | 0

Answered
I do not know why am I getting imaginary numbers.
Look at the following for the values of i you are using: log(1-i) E.g., >> log(-1) ans = 0.0000 + 3.1416i

8 días ago | 0

| accepted

Answered
multiplying matrix by another matrix element and using it in a command
You can use a loop QT = Q .* reshape(T,1,1,[]); e = zeros(size(QT)); for k=1:size(QT,3) e(:,:,k) = expm(QT(:,:,k)); % fi...

10 días ago | 1

Answered
Sparse matrix memory usage clarification
Sparse matrices can be allocated with more than the minimum memory to hold the non-zero elements and their row indexes (see nzma...

10 días ago | 1

Answered
How to name components of a vector to variables
Don't do that. Your downstream programming will be miserable if you do. See this link for better alternatives (cell arrays, st...

10 días ago | 0

Answered
How to assign values to a matrix from index array?
A(sub2ind(size(A),x,y)) = 1;

11 días ago | 0

Answered
Find Sum of array
It may be that you have a local variable called sum that is shadowing the MATLAB sum function. Try clearing it first: clear su...

12 días ago | 1

Answered
Using a function in another function
So, normally one would just have f in your work function. E.g., function work(f,a,b) if sign(f(a))~=sign(f(b)) error('a ...

12 días ago | 0

| accepted