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# Fabio Freschi

### Politecnico di Torino

174 total contributions since 2014

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How to color a mesh by temperature(or other value) preserving the elevation. Using two matrix(same length)
% dummy data [X,Y] = meshgrid(1:0.5:10,1:20); Z = sin(X).*cos(Y); T = X+Y; % plot surf(X,Y,Z,T) colormap('hot') colorba...

2 días ago | 1

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How can I get an array of velocity if I have an array of position and another array of time
First, you need a element-wise division pos = [0 2 4 8 16 32 64]; t = [0 0.1 0.2 0.3 0.4 0.5 0.6]; V = diff(pos)./diff(t); ...

2 días ago | 0

Numerical Solution for a System of THREE Differential Equations
This is an ODE, not PDE. Look for the ODE suite

2 días ago | 0

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Area under curves with different length (trapz)
If you have the x axes for both waves, it is pretty easy to use trapz: N1 = 1036; N2 = 9958; % wave 1 x1 = linspace(0,2*pi...

2 días ago | 1

Plotting the integral of a graph
Suppose that x and y are the vectors defining your waveform. % dummy values x = linspace(0,2*pi,1000); y = sin(x); % integ...

2 días ago | 1

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Does anybody know how to write a function which returns the coordinates of a convex hull of a list of certain points?
% your data N = 20; List = rand(N,2); % convex hull (k is the pointer to the rows in List with the convex hull k = convhul...

3 días ago | 0

How to divide a part of array to the another part of it?
T = psi2(1:5)./psi(end-4:end);

3 días ago | 0

How can speed up the blow codes?
Edit: added attempt for ncount I don't understand what ncount is doing, it looks like a counter but I don't understand why you ...

4 días ago | 0

defined n with the equation
n= size(P4,1)

19 días ago | 0

Array indices must be positive integers or logical values
Your index k starts from 0 and you are indexing h with k, so you are asking at the first iteration h(0). Matlab has 1-indexing s...

19 días ago | 0

while loop performance improvement
I don't know the starting value of k, assuming it is 1 idx = 1:rate:period mysum = sum(array(idx,2)); % note that sum is the n...

19 días ago | 1

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Euler method error in code Index exceeds the number of array elements (1). in my my code
Checking the sintax of the code only I see 3 issues 1) In the for loop you wrote a(400-x(n)), that is you are addressing the po...

19 días ago | 1

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Population growth in 7 years
% rate r = 0.0063; % years t = 7; % initial population a = 5e6; % population y = a*(1+r)^t

22 días ago | 2

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Apply operation to each element of an array
You should use element-wise operations https://it.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html In you...

22 días ago | 0

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How do you solve for a double sum
There are some things that are vgue, like the x-axis, in any case, this code shows something similar to the desired result clea...

24 días ago | 1

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Solving System of Equations
It seems you are solving a numeric system of equations. Why don't you simply put the coefficient matrix in A and the right-hand-...

25 días ago | 0

Finding values within a matrix
It is difficult to answer because we don't have the data files 'areatemp1' and 'machtemp1'. In any case in your if statement yo...

25 días ago | 0

Making a 3D Matrix and Adding Matrices to make a bigger matrix
In the loop, you wrote T(i+k-1,j+k-1) = d(i,j,k-1); k starts from one, so you are trying to access the d(i,j,0) elemen...

26 días ago | 0

Computational Electromagnetics and MATLAB

26 días ago | 1

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Why am i getting the : errir using inv ,Matrix must be square?
As James Tursa said, inv(H) is not defined when H is not square. If you have the matrix H and the rhs g, simply use f = H\g;

27 días ago | 0

Struggling to Vectorize the following Code.
Almost all execution time is due to the plot function as highlighted by the profiler: You can call the plot only once at the ...

27 días ago | 0

How can I pick certain element from each row of an array ?
I see that the edges shared by two triangles are not duplicated. To check for this case I sorted the nodes and the edges. Let me...

27 días ago | 0

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Combining my newton's method function for nonlinear equations and my lu decomposition function.
Is this what you are asking for? delta = LUgauss(J(x0),-F_value); Note that the buil-in lu Matlab function can do the work for...

29 días ago | 0

How to sum over rows within specific ranges without for loop?
Not sure if it is the best way, but this seems to work index = [0; cumsum(B)]; C = cell2mat(arrayfun(@(i)sum(A(index(i)+1:in...

29 días ago | 0

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Removing Outbound (out of range) data from an array
% dimension N = 1000000; % data in (0,1) x = rand(N,1); % threshold xMin = 0.25; xMax = 0.75; % remove data out of ...

30 días ago | 0

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How to select specific values and corresponding cell positions from 31 x 12 matrix?
Because the number of rows in B is not fixed, you can store the result of your check in a cell array % create the matrix A = (...

alrededor de 1 mes ago | 0

I have a problem with integration "Error using / Matrix dimensions must agree"
When you define your functions use ./ instead of / %function f=(x+(1./x)).^2; %real value of integral ff=@(x)(x+(1./x)).^2;

alrededor de 1 mes ago | 1

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Cause of: "Error: Inputs must be floats, namely single or double."
What I can see is 1) Fs is missing. In any case, tspan shpuld be a 2 entries array with initial and final values tspan = [0,15...

alrededor de 1 mes ago | 1

how to convert cell to matrix ?
A = cell2mat(cellfun(@str2num,x,'UniformOutput',false))

alrededor de 1 mes ago | 1