Answered
Error in ode45 while doing numerical integration
The function handle you pass to ode45( ) needs to have a (t,y) signature. E.g., [t,y] = ode45(@(t,y) myode(t,gt,g), tspan, ic, ...

2 months ago | 0

Answered
How to multiply higher order matrices?
You may need to permute your arrays first to get your desired 2D slices in the first two dimensions. A = whatever B = whatever...

2 months ago | 2

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Using matrix to index another matrix?
Does this do what you want: x = sub2ind(size(B),(1:size(A,1))',A(:,1),A(:,2),A(:,3)); Output = B(x);

2 months ago | 0

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Answered
Equivalent of c++'s NULL or python' s None in MATLAB
This will probably depend on how these are used downstream in your code and whether you have arrays of them to deal with. If th...

3 months ago | 1

Answered
X Y Z angles of a D20 (icosahedron) for gravity projection
If you have the 3D normal vectors, then all you need to do is take the dot product between them and the "flat" face normal vecto...

3 months ago | 1

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Answered
modify a row of an array within a function
This can sometimes be done inplace depending on how you write the function and how you call the function. One requirement is yo...

3 months ago | 0

Answered
Operator '-' is not supported for operands of type 'function_handle'.
You are using u as both an input argument and a global function handle function A3 = odeFun(t, u) <-- input argument global R...

3 months ago | 0

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Solve a system of 3 second order ODE
You will need to change your scalar equations to vector equations, and you will need to change your derivative function to a vec...

3 months ago | 0

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Need to speed up the generation of random numbers.
You could over generate a large matrix and then pick off the number of elements you need later. E.g., C = rand([5 size(A)]); T...

3 months ago | 0

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How do i create a large matrix with a formula?
N = 1000; a = 2 * pi * f * T * (0:N-1)'; x = [cos(a) -sin(a)];

3 months ago | 1

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Matrix multiplication to get covariance matrix
@Tintin Milou MATLAB variables do not have a "symmetric" attribute flag that I know of. Just because you create a variable that...

3 months ago | 0

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Why can't complex integer arithmetic be done?
I think the main reason for disallowing integer array arithmetic in MATLAB is because of the ambiguity caused by the max(min( ))...

3 months ago | 1

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How can I split C/C++ Code in multiple files and still use MEX
Use the -c option to compile the B and C stuff to produce only object files without any linking: mex -c B.c C.c Then compile y...

3 months ago | 1

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Answered
Matrix multiplication. Trying to get scalar solution
Those should be matrix multiples, not element-wise multiplies. Remove the dots. E.g., top=nMode * M * u0; bot=nMode * M * nM...

3 months ago | 0

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Answered
Adapt RK4 ODE Solver from first order to 2nd order
Try this for starters yt = zeros(numel(y0),length(h:tfinal)); %Memory Allocation And then maybe this is what is intended for i...

3 months ago | 0

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Answered
Error using vertcat Dimensions of arrays being concatenated are not consistent.
You have a mismatch in the number of arguments. E.g., this [V,y] = ode45(@(~,y) fun(del_h1,del_cp1,cp1),Vspan,y0); should be ...

3 months ago | 0

Answered
Replacing matrix n column values
E.g., temp = A(:,70:80); temp(temp<0) = 0; A(:,70:80) = temp;

3 months ago | 1

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Answered
Solving an overdetermined system of linear equations
Since you can simply plug in those values to verify that they satisfy all four equations, the conclusion would be that you have ...

3 months ago | 0

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Answered
How to create a cell array with binary numbers?
Your pop variable has 1000x11 = 11000 elements. Your for-loop only assigns values to 1000 of those elements (the first column)....

3 months ago | 0

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Vector sum of forces
sqrt(sum(F.*F,2))

3 months ago | 0

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invalid use of operator
You are missing a ( after the second "if", and you are missing an "end" statement. That being said, my suggestion would be to u...

3 months ago | 0

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Need Help Solving Two Coupled ODEs
The derivative function needs to have the input arguments specified. In your current code above, you have no inputs specified. ...

3 months ago | 0

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Answered
Versions of Euler Methods
methodA has a fundamental flaw: y(i+1) = y(i)+ h*func( t(i) + h/2, (y(i)+y(i+1))/2 ); You can't use y(i+1) on the right hand s...

3 months ago | 1

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Problem with matrix differential equation resolve in Matlab with ode45
Normally I would have expected ode45( ) to pass q as a 4x1 column vector. Also, I don't see anything in your code solving for q...

3 months ago | 0

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Answered
Question regarding quaternion conventions; particularly with respect to point vs frame rotations
See this post for comments regarding "point" vs "frame" convention: https://www.mathworks.com/matlabcentral/answers/524471-what...

3 months ago | 0

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Using vectorization to shorten run time
E.g., [P,D] = meshgrid(p,d); % generate all possible combinations X = [P(:) D(:)]; % combine them into side-by-side column vec...

4 months ago | 1

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Answered
why does dimension of input variable change in ode45
The dimension changes to a column vector because that is the way ode45( ) operates. Your derivative function needs to be able t...

4 months ago | 1

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Answered
Maatlab crash with .mex function
I had to make some assumptions about how the matrix data areas are supposed to be loaded. We can try this first to see if these...

4 months ago | 0

Answered
How to calculate standard deviation in double for loop?
The short answer is don't do that. This style of programming has many problems. See this link for alternatives: https://www.m...

4 months ago | 0

Answered
Add row to an empty array if a condition is fulfilled
No need for an explicit loop. Just use logical indexing: result = m(strcmp(m(:,3),'A'),:);

4 months ago | 0

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