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...

4 years 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...

4 years ago | 0

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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...

4 years 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...

4 years 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...

4 years 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)];

4 years 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...

4 years 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( ))...

4 years 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...

4 years 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...

4 years 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...

4 years 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 ...

4 years ago | 0

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

4 years 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 ...

4 years 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)....

4 years ago | 0

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

4 years 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...

4 years 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. ...

5 years 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...

5 years 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...

5 years 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...

5 years 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...

5 years 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...

5 years 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...

5 years ago | 0

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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...

5 years ago | 0

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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'),:);

5 years ago | 0

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Answered
reproduce random numbers for the third dimension
If you don't want the random numbers to change from iteration to iteration, then don't regenerate them inside the loop. Calcula...

5 years ago | 0

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Answered
Using an Array as an input
The error message actually tells you exactly what to do. Use element-wise operator .^ instead of the matrix operator ^ Energy ...

5 years ago | 1

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Runge-Kutta 2
The + 4.*x1 should be - 4.*x1 in your derivative function. Also, using both X1 and x1 and X2 and x2, even though MATLAB is case...

5 years ago | 0

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Answered
3D array of rotation matrices multiplied on 2D array of vectors
To answer your side question of how to transpose 2D pages of an array, you can use the permute function to swap the first two di...

5 years ago | 0