Community Profile # Fabio Freschi

### Politecnico di Torino

Last seen: 5 days ago Active since 2014

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smooth step function with rise time
My colleague Sofia have found a paper  where authors report the analytic approximation of the piece-wise linear step function...

29 days ago | 1

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Question

smooth step function with rise time
Hi everyone, I know this question is more related to math than Matlab, but I know there are many gurus out there who can easily...

1 month ago | 3 answers | 1

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How can I calculate the sum of the absolute error?
Please check the code below. clear all, close all % model F = @(c,x)c(1)+c(2)*x+c(3)*(x.^2-1); % data xk = [-2 -1 0 1 ...

2 months ago | 1

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Drawing a rotating circle on a sphere
The code should be self-explicative [X,Y,Z] = sphere; % figure figure, hold on axis equal, view([1 1 1]); % sphere wit...

2 months ago | 0

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Showing me wrong Matrix Size.
multiply without the 'dot' OO= N*kk;

2 months ago | 0

How can you solve a system of second order differential equation, which is not time, but length and radius dependent?
This is not an ODE but a PDE. you should have a look at pdepe

2 months ago | 2

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We have a column vector and a row vector both of same lengths. How to use sum function to get element wise sum of two vectors and final answer display in row vector
vect3 = vect1.'+vect2 If you want to be sure of the element by element sum, regardles the shape of the two vectors (row or colu...

2 months ago | 0

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How to randomly change element of matrix?
You can use linear indexing % your matrix A = rand(10,100); % create the folder mkdir('storage'); % loop for i = 1:100...

2 months ago | 2

How to create a series of circle by using a specific radius in cartesian?
Try something like this % anonymous function to plot a circle given the center coordinates and the % radius plotcircle = @(x,...

2 months ago | 0

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Converting Euler ODE to the MATLAB code
f is an anonymous function f = @(t,y)[-2*y(1)+y(2)+15*cos(t); 2*y(1)-y(2)]; note that your script is not correct, since t is t...

2 months ago | 1

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How to call a variable matrix from one script to another script
I am not sure I have understtod correctly your problem. I give it a try. I would add an extra layer using an anonymous function...

3 months ago | 1

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How to use ~= operator as constraint function?
You may have a look here or here

3 months ago | 0

How to compare two time signals with different amount of samples?
Use interp1 to resample your vector(s) in order to have the same length clear variables, close all % time vector t1 = 0:1/1...

3 months ago | 1

solve efficiently sparse large linear system of equations
I would let the backslash operator work on this matrix sol = L\f; Can you share the original matrix to make other attempts?

3 months ago | 0

how to use lsqnonlin to solve conditional equation
The following code should be self explainatory. In the opposite case, simply ask clear all, close all % some dummy params va...

3 months ago | 0

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how to ascribe two values to a parameter such that it will be time dependent
You can pass an extra parameter to RiceG1 function using an anonmymous function. In your driver function add % extra anonimous ...

3 months ago | 1

Can someone help me implement my Kuramoto Model with time delay please?
Your function requires additional parameters. One way to pass them is to use an anonymous function as extra layer % params N =...

3 months ago | 0

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Euler's method in matlab
Any ODE solver gives the unknown function(s) as result, not its derivative. So, yes, your results are x and y. Note that in you...

3 months ago | 0

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for loop/periodic implementation for number or arrays?
If you want to force the max and min values of your vectors, you can preprocess them x0(x0 < 1 & x0 > nx+1) = 1; If the bounda...

3 months ago | 1

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How to get this while cycle?
if B and C are matrices, make them vectors using : while any(abs(a_0-a) > 1e-6) || any(abs(B_0(:)-B(:)) > 1e-6) || any(abs(C_0(...

3 months ago | 1

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how to find out node coordinates for a simple quad element?
It depends on your data structure: now your qeustion is rather vague. Assuming that you have the node coordinates in the Nx3 ar...

3 months ago | 1

Hwo to normalize a Matrix ?
Following the formula of the OT the normalization has to be done according to the max and min of each row. Note that the matrix ...

3 months ago | 1

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Solving nonlinear DE by reduction of order on matlab
There are some typos in your description of the problem. Here the correct version % your ODE - note that (y(1) and y(2) are exc...

4 months ago | 0

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creating array based in another array
Here a possible solution, where all arrays you want are in the columns of matrix a2 % number of entries in array 1 n = 5; % c...

4 months ago | 0

Warning: Matrix is singular to working precision.
The matrix is singular because the first three rows are linearly dependent. For example you can obtain row 1 as I guess there...

4 months ago | 0

how can i let all number in matrix X between 0~1?
If you want to scale your output in [0 1] you can use this X1 = (X-min(X))/sum(X-min(X)); in fact >> sum(X1) ans = ...

4 months ago | 0

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how to shift the plotting graph?
Not sure if it is what you want, but you can change the x-axis limits in this way: set(gca,'xLim',[5 20]) to show the portion ...

4 months ago | 0

Question

Real time GMRES convergence and stop callback
Dear Matlab users, I usually solve large linear problems using gmres. These simulations could last for several tens of hours. T...

4 months ago | 0 answers | 0

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Population growth in 7 years
Below you can find the output of the following code % rate r = 0.0063; % years t = 7; % initial population a = 5e6; t =...

5 months ago | 1

Question

Problem with Simscape variable visibility
Hi all, I have created a simulink model of a circuit using simscape electrical elements. I have also created two callbacks, Ini...

10 months ago | 1 answer | 0