# David Sanchez

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Physicist, working as control engineer for a wind turbine manufacturer. Professional Interests: control,optimization, computer vision, robotics, renewable energies.

**Programming Languages:**

Python, C++, C, MATLAB

**Spoken Languages:**

English, French, Spanish

**Professional Interests:**

Control Systems, Physics, Engineering, Renewable Energy

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**Feeds**

why is it not plotting or graph? it comes out blank

Hi there, if you run your code by blocks, after finishing the first while loop, you end up having: x = 0 0.5000 ...

2 years ago | 0

Create a plot with values from matrices of many dimensions.

Hi Stelios, it seems you are trying to plug 4D matrices into the surfc function, and as you mention: surfc: "Value must be a ...

3 years ago | 0

| accepted

How to save data in for loop to excel

Hi Jidapa, type in your matlab terminal doc xlswrite This will give you lots of information about how to do it. As an example...

3 years ago | 0

| accepted

Control systems failing to plot

Hi Daniel, your problem has definitely to do with your PC for sure. As you mention, the code works in your colleagues machines (...

3 years ago | 0

i can not figure out what is wrong with my code,when i call my function it does show eny outpout

Hi Tasos, your nested "ff" conditions only contemplate cases for temp(i) equal to 10, 20, 30 or 40. When temp(i) is differente t...

3 years ago | 0

| accepted

Cut Sinusoidal signal in a integer number of periods

Hi, bear in mind that the sampling of your curve might play an important role in the game. The code below might help you out: ...

5 years ago | 1

| accepted

State observer bode plot

Hi, I'm sure that you can find an example similar to your problem in the Bode documentation: https://mathworks.com/help/ident/...

5 years ago | 0

| accepted

How I can split a matrix in four matrixes

M = rand(1001,3); % your matrix L = size(M,1); % L = number of rows n = floor(L/4); % number of rows for your matrices ...

8 years ago | 0

Respected sir, i have code for extracting ROI from dorsal hand image, my problem is to read and save multiple images from folder. in following code only single image has read and save but i want multiple images to read and save please help me.

Hi, firstly, your way of asking the question does not make it easy to help you. Your code presentation is really annoying, but ...

8 years ago | 1

| accepted

Saving a file with name of reference of other file name ?

Hi, it all depends on how the user introduces the *.stl file name, but taking for granted that the name is somehow available to ...

8 years ago | 0

I have a 6000x9424x50 matrix and want to convert it into 6000x9424x10 and 6000x9424x20?? I meant to to split 50 bands to 10 or 20 bands individually?

your_matrix = rand(6000,9424,50); % random matrix M_10 = your_matrix(:,:,1:10); % 10 bands M_20 = your_matrix(:,:,11...

8 years ago | 0

| accepted

How do I index within a structure?

% dummy struct your_struct.field_1 = rand(5,1); your_struct.field_2 = rand(5,1); % array with field-mean your_...

8 years ago | 1

Clean way to find which elements of categorical array are part of a set of labels

I think you are looking for this: data = {'a', 'b', 'c', 'b', 'a'} ; members = {'a','b'}; ismember(data,membe...

8 years ago | 1

| accepted

How do I ajust the vallues the X-axis of a mesh (Z,Y,X) plot?

hi, adjust this example to your needs: [X,Y] = meshgrid(-8:.5:8); R = sqrt(X.^2 + Y.^2) + eps; Z = sin(R)./R; ...

9 years ago | 0

Apply code on matlab files in different directories ?

From Documentation: path(path,'newpath') adds the newpath folder to the end of the search path. If newpath is already on the ...

9 years ago | 0

How to execute fft and ifft

Hi thereb, the sine wave is right there, but the problem is that after FFTing the your _y_ data, _YfreqD_ contains half the sam...

9 years ago | 0

| accepted

changing names of files

% Renaming a File in the Current Folder % In the current folder, rename oldname.m to newname.m: % movefile('oldname.m','...

9 years ago | 0

the code wont display an answers calculated

Hi there, after reordering your code, I saw it follows this structure: method=='f' --> n= 1,2,3,other_value meth...

9 years ago | 0

Adding phase noise in simple signal

Hello Kutru, I do not know exactly what were you expecting to find in your plots. The difference in your plots is only the nois...

9 years ago | 0

The expression to the left of the equals sign is not a valid target for an assignment.

You are using the notation used by numeric::int instead of that to int Take a look at their differences in the ...

9 years ago | 0

how can store multiple value in a matrix??

ncadre=15; nbclasse=1000; load('D:\Documents\MATLAB\classifieur1.mat'); load('D:\Documents\MATLAB\classifieur2.mat');...

9 years ago | 0

| accepted

Efficient Frontier code error

Watch the last line of code: print portfolio03.ps - deps ; Mind the blank space right before deps simply delete it: ...

9 years ago | 0

| accepted

error in working with cell array

hi, transform C into a matrix before concatenating A, B and C in result: C = cell2mat(C); result={A; B; C}; mydat...

9 years ago | 0

How to replace data in a matrix by comparing from another matrix?

for k=1:length(B) x = A(:,1)==B(k,1); B(k,2) = A(x,2); end B = 1 5 ...

9 years ago | 1

| accepted

How do I loop through incrementally changing values

alpha = 1:0.5:20; a = 0.1+3*10^-3 * alpha.^2; b = 0.2+0.1*alpha - (3*10^-3)*(alpha.^2); c = 1./tan(-a./b); % I don't ...

9 years ago | 0

Good way to import data file

I'm sure this might be shorter, but I guess it'll be a valid solution for you: fid = fopen('your_file_name_here.txt'); ...

9 years ago | 0

how to select particular cell in the cell array and particular column in that cell array

You have to add new values to old ones: % initialize your data (I do it with empty array to make it easy) X0 = []; Y0...

9 years ago | 0

How do I find the two smallest values in varargin?

function out = two_lowest_values(varargin) a = sort(cell2mat(varargin)); out = a(1)*a(2);

9 years ago | 0

| accepted

Using Meshgrid for 3 variables

Make sure the size of d is right: If length(a) = n and length(L) = m, then, you have to have size(d) = [m x n] for example...

9 years ago | 0