Answered
Index in position 1 is invalid. Array indices must be positive integers or logical values.
Looks like you changed the definition of what f_m is in your code. In these lines f_m appears to be an array intended to hold va...

3 months ago | 1

Answered
What does A(2:4) = [ ] do if A is a 3x3 matrix?
This is linear indexing. Even though the variable is a 2D matrix, MATLAB allows you to index into it using only one index. The l...

3 months ago | 1

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error using function code
Create a file called lettergrade.m somewhere on the MATLAB path (e.g., in your working directory) edit lettergrade.m Copy all ...

3 months ago | 0

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dynamic naming of structures
Would it be acceptable to use x as a dynamic fieldname instead of the top level variable name? E.g., v.(x).a v.(x).b

3 months ago | 1

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How can I define an array of sparse matrix? (both for GPU and CPU)
For CPU, you can use the ndSparse submission by Matt J on the FEX: https://www.mathworks.com/matlabcentral/fileexchange/29832-n...

3 months ago | 0

Answered
numerical integration with recursive trapezoid rule
Some issues are immediately apparent. First, you don't reset S=0 inside the while loop. Isn't S supposed to contain only the a...

3 months ago | 0

Answered
Store every N columns in a Matrix to a new Matrix
Don't create a bunch of new matrices with hard to use names downstream in your code. Instead, simply reshape your matrix and the...

3 months ago | 0

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Answered
MEX file always crashes when I run it
In the MATLAB code you have this: np=single(np); Then inside the Fortran gateway routine you have this: mwPointer xr, yr, n ...

3 months ago | 0

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Answered
How can I reshape a matrix this way
a=[-0.26,0.23,0.033,0.1,-0.39,0.30;0.30,-0.39,0.10,-0.26,0.03,0.23;-0.03,-0.13,0.16,0.33,-0.16,-0.16] b=[-0.26,0.23,0.033;0.1,-...

3 months ago | 0

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Answered
Matlab while loops with equations
You should probably go through the online tutorials for learning MATLAB. But I will give you an outline to get started: toleran...

3 months ago | 0

Answered
i need to find error in code because I it's increasing but it should be decresing
You need to use all the derivatives at the first point to propagate for the initial guess at the second point. I.e., these lines...

4 months ago | 0

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t = 2 s, i = √−1, and 𝜔=120π rad/s. Evaluate the following using MATLAB? Hint: exp(n) is used in MATLAB to evaluate en. (a) e−2𝑡𝑐o𝑠 (𝜔𝑡)
I am guessing that the original expression shown is supposed to be interpreted as: Then take the hint at how to evaluate the ...

4 months ago | 0

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Why is my projectile motion code only working at certain input angles.
Drag depends on current velocity, not initial velocity. So you need to recalculate V at each step. E.g., Vx = Vx_new; Vy = Vy_...

4 months ago | 0

Answered
Sine equation in Euler Method ODE
You've only got one scalar differential equation, so I don't understand why you think you need two variables x and y along with ...

5 months ago | 0

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subtract matrix from vector
Just learn how to use indexing and element-wise operators. From your language, here are the pieces: subtract - the first thre...

5 months ago | 0

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Answered
How can I create arrays with different names using loop?
Don't embed numbering into the variable names. This will make the variables hard to use downstream in your code. Use cell arrays...

5 months ago | 0

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How to subtract each column of a matrix from a column vector?
Just do a usual subtraction and let MATLAB implicit expansion kick in: M = your matrix v = your column vector result = v - M;...

5 months ago | 0

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Simple mex file crash?
You need to create the output variable yourself. plhs[0] doesn't exist until you create it, thus this line crashes: outData = m...

5 months ago | 0

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Simulating Projectile with Matlab
You don't show us both methods (with and without drag) so we can't compare them. I presume you simply set k=0 for the case witho...

5 months ago | 1

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Answered
Matlab simulation for planet motion
The initial condition for position and velocity need to be outside the loop, prior to loop entry.

5 months ago | 1

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Answered
Vector ODE solution is not periodic/ as expected
This index 4 dxdt(4) = -DU^2* x(3)/sqrt(x(1)^2+x(2)^2+x(3)^2)^3; needs to be index 6: dxdt(6) = -DU^2* x(3)/sqrt(x(1)^2+x(2)^...

5 months ago | 0

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Answered
How to compile a Fortran subroutine by using the MEX engine
It looks like you are taking input, calling a MATLAB function, and getting output from that function. I still say it would be ea...

5 months ago | 0

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Answered
How to create Matrix [1 2 3 4; 2 4 6 8; 3 6 9 12; 4 8 12 16] without using loops or any functions using loops?
n = 4; % whatever result = (1:n) .* (1:n)' % use implicit expansion row .* column

5 months ago | 2

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Answered
Vectorising Multiplying each column from a matrix with a square matrix and the tranpose of this column
If you need the same column on each side of the multiply, then maybe this: result = sum(h'*Pn.*h',2);

6 months ago | 1

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Problem in using mxSetPr with USHORT
To attach pointers of type other than double to an mxArray, you can use the mxSetData( ) function as Jan suggests. In your case ...

6 months ago | 1

Answered
Beginner coding; my second, simpler approach at trying to make all elements distinct.
FYI, to generate random integers you can use the randi( ) function instead of ceil(value*rand( )): https://www.mathworks.com/he...

6 months ago | 0

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How to make a "page transpose" in a 3D matrix without using the function pagetranspose?
Mtranspose = permute(M,[2 1 3]);

6 months ago | 2

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Answered
How to multiply an inverse matrix (nxn) by an array (nx1) using for loop
Not sure why you have a for-loop at all. Maybe you can explain this. If you just want to multiply the explicit inverse by a vect...

6 months ago | 0

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Adding numbers to an array
You don't really need both h and hnew. Just use h and some indexing. E.g., h = zeros(1,45); % allocate expected result k = 1; ...

7 months ago | 0

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Answered
rounding issues in matlab, need to force values to 0
Instead of if abs(y1)< 1e-6 y1=0; end try y1(abs(y1)<1e-6) = 0;

7 months ago | 2

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