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MATLAB Programming

377

Solutions

450

Contributors

MATLAB is a numerical computing environment and proprietary fourth-generation programming language. MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages, including C, C++, Java, Fortran and Python. Although MATLAB is intended primarily for numerical computing, an optional toolbox uses the MuPAD symbolic engine, allowing access to symbolic computing capabilities. An additional package, Simulink, adds graphical multi-domain simulation and model-based design for dynamic and embedded systems.

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hi to all,

I have a vector in Matlab which contains samples acquired at 10Hz from an accelerometer mounted on a frame's vehicle.
This vector contains the acceleration values along the Z-axis.
The acquisition time is 103 seconds.

I would like to plot the frequency values in Hz since I'm trying to study the terrain frequency response.

I tried to use the fft function available in Matlab, but I do not know how to proceed.
Can you help me, please?

These are the values contained in my vector:

size(vibration)
ans =
        1024           1
vibration =
   -0.0005
   -0.0006
   -0.0007
   -0.0008
   -0.0010
   -0.0011
   -0.0012
   -0.0013
   -0.0014
   -0.0015
   -0.0016
   -0.0017
   -0.0018
   -0.0019
   -0.0020
   -0.0021
   -0.0022
   -0.0023
   -0.0024
   -0.0026
   -0.0027
   -0.0025
   -0.0003
   -0.0038
   -0.0089
   -0.0035
   -0.0018
   -0.0022
    0.0004
    0.0034
    0.0063
   -0.0023
   -0.0046
   -0.0022
   -0.0043
    0.0041
    0.0025
    0.0024
    0.0037
    0.0050
    0.0060
    0.0012
    0.0058
    0.0019
    0.0008
    0.0009
   -0.0060
    0.0004
    0.0032
   -0.0005
   -0.0008
   -0.0024
    0.0021
    0.0009
   -0.0019
    0.0003
    0.0012
    0.0069
    0.0125
    0.0209
    0.0262
    0.0184
    0.0100
    0.0058
    0.0136
    0.0181
    0.0089
    0.0058
    0.0077
    0.0045
    0.0024
    0.0015
    0.0044
    0.0095
    0.0096
    0.0087
    0.0019
    0.0053
    0.0066
    0.0033
   -0.0010
    0.0010
    0.0116
    

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This code works for White particles on a black background, can it be tweaked to work for black particles on white background..?Thanks!

 
    RGB=imread('CW5000.jpg');
    s_wavelength=4; ; %use every 4th pixel for the perimeter calculation
    I = rgb2gray(RGB);
    threshold=.4 %black and white threshold
    bw = im2bw(I,threshold);
    imshow(bw)
    bw = bwareaopen(bw,350);
    se = strel('disk',2);
    bw = imclose(bw,se);
    bw = imfill(bw,'holes');
    [B,L] = bwboundaries(bw,'noholes');
    imshow(label2rgb(L, @jet, [.5 .5 .5]))
    hold on
    for k = 1:length(B)
    boundary = B{k};
    plot(boundary(:,2), boundary(:,1), 'y', 'LineWidth', 1)
    end
    stats = regionprops(L,'Area','Centroid','MajorAxisLength','MinorAxisLength')
    for k = 1:length(B)
    boundary = B{k};
    A = size(boundary)
    boundary2=boundary(s_wavelength:s_wavelength:A(1,1),:);
    delta_sq = diff(boundary2).^2;
    perimeter = sum(sqrt(sum(delta_sq,2)));
    area2 = stats(k).Area;
    area=polyarea(boundary2(:,1),boundary2(:,2));
    metric = 4*pi*area/perimeter^2;
    metric_string=sprintf('%2.2f',metric);
    text(boundary(1,2)+0,boundary(1,1)+50,metric_string,'Color','k',...
    'FontSize',12,'FontWeight','bold');
    %text(boundary(1,2)+40,boundary(1,1)+100,metric_string2,'Color','c',...
    %'FontSize',12,'FontWeight','bold');
    %text(boundary(1,2)+30,boundary(1,1)+150,metric_string3,'Color','g',...
    %'FontSize',12,'FontWeight','bold');
    

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0
Hi to all,

I have a vector " imu" with a size of 11497 elements. These elements are samples captured at a very high rate (the total time is 71 seconds so I think the frequency is about 160 Hz). Since I acquired all the other values at 10Hz, the size of all my other vectors is 719.

I would like to remove the oversampled elements from the vector " imu" in order to have only 10 samples per second.

Is there any way to do this? Can you help me, please?
0
Hi to all,

i'm having a problem with one of my old matlab scripts.
This script worked very well on a previous version of Matlab, but now I'm running it on a different machine and on a different Matlab version (R2017b) and it gives me this error:

Index exceeds matrix dimensions.
Error in cusum (line 36)
y   = x1(:,c_y) - mean(x1(:,c_y));
Error in original (line 269)
      [ckc,slc]=cusum(Ic(:,2)); %% PROBLEMA 

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Please, can you try to help me?
I attached to this post all the matlab files (i renamed them with *.txt extension) and also the txt file to use to populate the vectors.

The main matlab file is 'original.m':

clear all, close all
addpath '/home/rocco/Documents/MATLAB/code/function'
% 
% figure(1)
% set(1,'units','normalized','position',[0.142187 0.484722 0.307813 0.447222],....
%         'name','Path','numbertitle','off');
%     set(gca,'FontSize',11);
% figure(2)
% set(2,'units','normalized','position',[0.457031 0.484722 0.264063 0.447917],....
%         'name','Equivalent track','numbertitle','off');
%     set(gca,'FontSize',11);
%     
% figure(3)
% set(3,'units','normalized','position',[0.009 0.13 0.482031 0.806944],....
%         'name','Terrain estimation','numbertitle','off');
%     set(gca,'FontSize',11);
%     
% figure(4)
% set(4,'units','normalized','position',[0.00351563 0.0465278 0.214453 0.893056],....
%         'name','Path','numbertitle','off');

%% Load data

% First campaign january 2015

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0
I am trying to use Matlab 2016 as a neural network. I have large amounts of comma-delimited ASCII data that I would like to analyze. Each row of data contains about 1500 elements of alphanumerics. There would be about 100 records/rows of 1500 elements each. The first task I need to do is determine the correlation, if any, between the various elements. I think that would be a clustering issue. Is it practical, or advised, to try to run the entire block of data at one time, or to pick out what I think are the relevant factors and just analyze those for correlations? I have reasonably powerful computing equipment and I don't know if time factors would make looking at the entire data set prohibitive. Once I determined which way to do that, and have figured out some of the correlations, I would then have to set up an actual neural network to try to get some insight into larger blocks of that same type of data.

Any help will be appreciated and points awarded. Thanks.
0
HI

I have angles of head movements for each video frame in radians ,where positive values yaw correspond to head turning right and

negative values corresponds to head turning to the left .

 I need to calculate movement dynamics ( angular displacement , angular velocity ,angular acceleration )
yaw.csv
untitled.jpg
0
(i) Develop an algorithm to determine whether a graph represented by a node-node incidence matrix is connected or not. Provide a clear algorithm statement.
(ii) Code your algorithm in any programming language you prefer, run your code on the node-node adjacency matrices. The matrix is 300x300. Also, I need to report my results along with the computation time in seconds
0
When I compile my mex with the "-g" argument, a PDB file is created which allows me to Attach to the Matlab Process.

This works OK.

However, I'm finding that if I change any part of the source code, then recompile the mex and Attach to Matlab again, my breakpoints are not ever hit again.

The solution is to exit Matlab, restart Matlab, rebuild the  mex and re-attach.  Then, magically, it works again.

But it's a royal pain to have to continue exiting Matlab every time I make a small code change.

Does anyone know what the solution is?

Thanks,
0
Hi,
I am trying to check integration using two different methods, first by using [function (int)] and second by using summation. I am integration from high to low values (0.1 to 0). I got same result. However, from function I got positive value (0.005) and from summation, negative value (-0.005).  I am not sure if that because I am integrating from high to low values so I need to use (dr) in negative value when finding the integration using summation.

I used below code

 
 clear all;
  clc;
  syms x y 
  y = -x; 
  z=int(y,x);
  v=[0:0.1/19:0.1];
  dr=0.1/20;
  for i=1:20
      x=v(i);  
      kk(i)=eval(y)*(dr);    
  end
  R1=sum(kk(1,:));
  x=0.1;
  z1=eval(z);
  x=0;
  z2=eval(z);
  R2=z2-z1;

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0
You can refer to section 4.3.1 in this article if you want.

Problem: Given a reference point and a direction, I need to find the core of a line scratch.


  1. To do that, according to the article, I need to select a prominent point on the line-scratch and that point would be used as the reference point pR.
  2. Then start a search from that reference point, proceeding on both sides of the line along the direction dS.
  3. If pI is our current point at column k (shown in yellow here),
    • take 5 points adjacent to pI at column k+1 (shown in blue here).
    • find the point with the largest similarity value.
    • add the point to the core.

pixel-candidatesWe will use a specific function as the similarity measure. That function uses correlation, among other things, as a measure.

equation
  1. pI is the i-th pixel at the column-k.
  2. w1 and w2 are constants with values 0.75 and 0.25 respectively.
  3. cG is a global correlation factor measured between a matrix centered at pR and another matrix pKi which has a center at pI.
  4. g is a Gaussian function computed at pI.
  5. cL is a local correlation factor measured between a matrix centered at pK_1s and another matrix pKi which has a center at pI.
  6. pK_1s is the last included point at the core.

Implementation
Please, see the source code later in this question.

What is the problem I am facing right now?
 
  1.  I am not sure whether the matrices (i.e. pKi, matrix around pR, pI and so on) I am using are taken correctly.
  2.  I am not sure about the usage of dS.
0
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One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

I am very new to image processing and Matlab. I am working with RGB image and used SLIC algorithm to generate superpixel for an image. By using regionprops to calculate the superpixel properties.

[Rcounts binlocations]=imhist(ImageRED);
[Gcounts binlocations]=imhist(ImageGREEN);
[Bcounts binlocations]=imhist(ImageBLUE);
Q1: I have 48 superpixels with Counts(R,G,B channels) it is giving me 256*1 double(most of them are zero). Can anybody explain how to refine them to get each superpixel histogram?

Q2: How can I compare and calculate the distance between two specific superpixel histograms?

Any help is greatly appreciated. Thanks in advance
0
how can I add a constraint for vibration damper in a SUV vehicle model meant to demonstrate a rollover
0
Hi,

I have a covariance matrix and I am using Matlab's chol function for cholesky decomposition. However, since my matrix is not a positive definite matrix. I am getting an error. How can I figure out which correlations/covariances in the matrix are leading to the problem.

Attached file contains the matrix.

Thanks
EE1.xlsx
0
How to write program for  encryption and decryption input text using RC4 algorithm in Matlab?
0
how i can apply fuzzy logic for this problem? Or is there any other technique i can use for my problem?

Input : parameter values Output : (1) OLTP , (2) DSS , (3) % of OLTP and % of DSS

I have to classify between 3 classes as OLTP, DSS and mix type. if my input matches with OLTP or DSS type it return crisp class. if it matches with mix type it returns the percentage of OLTP and DSS
0
How can i apply fuzzy logic for this problem? Or is there any other technique i can use for my problem?

Input : parameter values Output : (1) OLTP , (2) DSS , (3) % of OLTP and % of DSS

I have to classify between 3 classes as OLTP, DSS and mix type. if my input matches with OLTP or DSS type it return crisp class. if it matches with mix type it returns the percentage of OLTP and DSS.
0
Two vehicles update their position using latitude and longitude using .csv file. Plot the graph for two vehicles in a single graph to detect the collision.
0
I have attached the file of Matlab output. How to detect the intersection points red dots. Whenever it detect the red dot at intersection alert message should be displayed.
curveintersectionsexample.png
0
As a part of my project, I want to encrypt user defined data using an unbreakable encryption algorithm. I have got one AES algorithm. But it accepts plaintext as
 plaintext_hex = {'00' '11' '22' '33' '44' '55' '66' '77' ...
                 '88' '99' 'aa' 'bb' 'cc' 'dd' 'ee' 'ff'};
I am doing my project in matlab.
0
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Question :You are to simulate the motion of a drunken sailor (i.e. a random walk problem).  The sailor is standing at the middle of a pier on the shore side.  The sailor’s ship is directly across from him.The pier size is L paces long and W paces wide (i.e. the sailor starts at coordinates ½ W, 0 and the ship is L paces away) and the ship stretches across the entire width of the pier.Due to the sailor’s inebriated condition a straight walking path cannot be maintained.  Each second the sailor attempts to take a step.  There is a 25% chance that the sailor will go left, a 20% chance the sailor will go right, a 10% chance the sailor will stand still, and a 45% chance the sailor will go forward.  Assume the sailor does not go backwards.If the sailor’s position exceeds the dimensions of the pier (zero to W) they fall into the sea.  If they make it to the other side they are safe at their ship.Write a  Matlab program(script file) that takes L and W as user inputs.  The motion of the sailor is then simulated.  If the sailor falls into the sea an appropriate message should be output.  If the sailor makes it to the ship the time and number of paces it took them should be output.  For either case a plot showing the sailor’s path should be made.
Hint: Use evenly distributed random numbers to determine what direction the sailor goes.
0
Hi, I am beginner in Matlab, need help or advise on how to do this? If i have 2 image in gallery (one basketball image and one badminton image)-Basketball.JPG/Badminton.JPG I created GUI. Then i am able to upload the one of the image. But how do i compare this upload image with the 2images in gallery. So that if uploaded image matches Basketball, it will display Basketball. and if uploaded image matches Badminton,it will display Badminton.
0
Hi

I have .csv file with two cols . I need to take 13 values from 1st col then 13 values from 2nd cols and make then as one row with 26 col

until the end of file .
zju_25_5.csv
0
Hi

in the following code I'm searching for a match of indexes between 2 files , if I found a match take -6,6 elements from the 1st file .

I need to save the found data as (1,13) . (data ) array shows the elements as I print it when I run the code  but after finishing executing only the last element is saved .

earFilename = 'EAR_v1.txt';
stateFilename = 'output_close_tags_video_1.txt';

% read EAR values
 earfile = fopen(earFilename,'r');
 formatSpec = '%d %f %f';
 sizeA = [3 Inf];

earVector = fscanf(earfile, formatSpec, sizeA);
earVector = earVector';

% read state file
 statefile = fopen(stateFilename,'r');
 formatSpec = '%d %*s';
 sizeA = [1 Inf];

   stateVector = fscanf(statefile, formatSpec,sizeA);
   stateVector = stateVector';

% create a dataset containing framenumber, EAR, state
dataset = [earVector, -1*ones(size(earVector,1),1)];

% for each positive state, +-6 frame are marked as positive
data=[];
for i = stateVector'
  rowNumber = find(dataset==i);
  for j = -6:6
      data=(rowNumber+j);
      disp(data)

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I want to find dct of a matrix in c++ just like how it is done in matlab.
Below is the code I used
#include <fftw3.h>
using namespace std;
 double** create2DArray(int row, int col)
{
	 double** arr = new  double*[row];
	for(int i = 0; i < row; i++)
		arr[i] = new  double[col];
	return arr;
}

int main()
{
int m = 3; 
int n = 3;
 	
      /*double a[m][n] =
   	 {
        {0.2, 0.3 ,1},
        {0 ,12 ,5},
        {0.3, 0.3, 1}
   	 };*/

   double** a= create2DArray(m,n); 
   for( int j = 0; j < m;j++ ) 
  	{	
  		for(int i = 0; i < n; i++)
	   		{	
    						a[i][j] = Signal[i]*hamming[i];
			}
  	 }

   double** b= create2DArray(m,n);   
   
    printf("Original vector\n");
	for(int i=0;i<m;i++)
	 {    
	  for(int j = 0 ;j<n;j++)
	     {
	        cout << a[i][j] <<"  " ;
	     }
	cout<< endl;
	}
  
    

    fftw_plan plan = fftw_plan_r2r_2d(n, m,&a[0][0],&b[0][0], FFTW_REDFT10, FFTW_REDFT10, FFTW_ESTIMATE);
    fftw_execute(plan);
      
    printf("DCT\n");
    for(int i=0;i<m;i++)
	{    
	for(int j = 0 ;j<n;j++)
		{
	cout << b[i][j] <<"  " ;
		}
	cout<< endl;
	}

    
    fftw_plan plani = fftw_plan_r2r_2d(n, m,&b[0][0],&a[0][0], FFTW_REDFT01,  FFTW_REDFT01,FFTW_MEASURE);
     fftw_execute(plani);
    
    printf("IDCT\n");

    
   	for(int i=0;i<m;i++)
	{    
	for(int j = 0 ;j<n;j++)
		{
	cout << a[i][j]/(m*n*4) <<"  " ;
		}
	cout<< endl;
	}
   
  
    return 0;
    

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1) Matrix a[m][n] is obtained by multiplying signal with hamming window .
2) When I pass Matrix "a" as input to     " fftw_plan plan = fftw_plan_r2r_2d(n, m,&a[0][0],&b[0][0], FFTW_REDFT10, FFTW_REDFT10, FFTW_ESTIMATE); "
I get the following error :
 cannot convert ‘long double*’ to ‘double*’ for argument ‘4’ to ‘fftw_plan_s* fftw_plan_r2r_2d(int, int, double*, double*, fftw_r2r_kind, fftw_r2r_kind, unsigned int)’

How do I pass a matrix  to DCT function using fftw3 ,which is declared as mentioned above .
PS :When I declared it as double a[m][n] = {//Enter the elements}; //when m =640 ; n = 645
It gives Segmentation fault
{Because of which I tried to define matrix a in heap as mentioned but when given to the dct function throws error .}

Can anyone kindly solve my issue .
Thanks in Advance.
0
So I was trying to convert my matlab codes to c++ codes .I was trying to compare the output of all the user defined function written in matlab and c++ . In terms of precision there was slight difference . Something like   " 0.0822219583523415  " the output from matlab   and " 0.082222" from c++ . I ignored such difference at first as the result was similiar to some extent .But when operations like DCT and IDCT is done on vectors with such difference in values , the output I obtained from matlab and c++ DCT /IDCT was very different .
How can I solve this problem ?
0

MATLAB Programming

377

Solutions

450

Contributors

MATLAB is a numerical computing environment and proprietary fourth-generation programming language. MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages, including C, C++, Java, Fortran and Python. Although MATLAB is intended primarily for numerical computing, an optional toolbox uses the MuPAD symbolic engine, allowing access to symbolic computing capabilities. An additional package, Simulink, adds graphical multi-domain simulation and model-based design for dynamic and embedded systems.

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