Error of array value in loop( for for while)

Hello everyone! I am trying to make a code that would calculate BPM from PPG. the original signal has artifacts from poor handling of the sensor so i am also trying to get rid of enormous peaks that are present. I have encountered an odd error when using 'while' in a 'for' loop. DeltaT must be a vector, without while it recognizes it but douse not stop after reaching max length of the input. Once i put while in the loop, the resulting deltaT is still a vector but has the value of the last calculation. i fail to see what is my mistake. please help me to solve this interesting problem. Kind regards!

n=load('ppg.mat');
ppg=n.data(:,2);
t=(0:(length(ppg)-1));
f_s=1000;
N=length(ppg);
T=[0:N-1]/f_s; %time period(total sample/Fs )

w=50/(f_s/2);
q=34;
bw=w/q;
[b,a]=iirnotch(w,bw); % notch filter implementation 
ppg_f=filter(b,a,ppg);
N1=length(ppg_f);
t1=[0:N1-1]/f_s;

% figure
% plot(ppg_f,'r');              
% xlabel('time')
% ylabel('amplitude')

t = 1:length(ppg_f);
[~,locs_Rwave] = findpeaks(ppg_f,'MinPeakHeight',0.4,...
                                    'MinPeakDistance',600);
% Remove Edge Wave Data
locs_Rwave(locs_Rwave < 150 | locs_Rwave > (length(ppg_f) - 150)) = [];
x=locs_Rwave.';
 frecventainstantanee=ones(1,length(x));
timpobataie=ones(1,length(x)-1);
  deltaT=ones(1,length(x)-1); 
r=length(x);  

   for(o=1:r)
       for(j=1:r)
         while(o<r )

           deltaT(j)=x(o+1)-x(o);
           o=o+1;
           j=j+1;                          
         end          
       end
   end
        end

[KALYAN ACHARJYA]

if OK/problem, let me know?

[Cristina Soltoianu]

Hi, again. I appreciate your willingness to help me, although i still get an error message saying ”Index exceeds matrix dimensions”

[KALYAN ACHARJYA]

I am sure while condition problem solved, which line the error?

[Cristina Soltoianu]

this is the error message that pops out:

Index exceeds matrix dimensions.

Error in dinacqcopy (line 42)
         deltaT(j)=x(o+1)-x(o);

my guess is that the loop douse not stop at (r-1). I have tried to set it at r-2, but the same message is showing. What a kerfuffle.

[KALYAN ACHARJYA]

send me ppg.mat

[Cristina Soltoianu]

I have attached it on the original question, but i will attach it again here.

Thank you for your time and effort

[KALYAN ACHARJYA]

I have edited the answer and provided code below. Now No error.

[KALYAN ACHARJYA]

Done??

[Cristina Soltoianu]

The code works, no error displayed. But if you check the variables,in the array deltaT all values are equal, which is the value of the last calculation done in the loop, where it should have different values. I am sorry to impose.

[KALYAN ACHARJYA]

definitely, you get the same value. see deltaT(j) expression, both having o

    % code
  deltaT(j)=x(o+1)-x(o); 

when j for loop exucated, it go to next o value, again insite loop run from j=1 to r-1 or r

one 'o' should be j, then only you will get different vales in same line like I have tried following and got the different results, wheather it technically correct or not, I dont know-

    % code
  deltaT(j)=x(o+1)-x(j)

[KALYAN ACHARJYA]

I have answered as per your question.I have another assignment now. More help needed later, I wl help you.

[Cristina Soltoianu]

Thank you. For now I have accepted your answer and voted. Hope to hear from you again.

Good luck!

[KALYAN ACHARJYA]

I have mentioned the solution how you get the different values in above comment. Check it, but I don't know the technically correct result or not. Mail

[Cristina Soltoianu]

I will work on it again tomorrow. for now i am only happy that I got rid of the error and display of different values. I will let you know!

It's been a pleasure!

Answer 1

[KALYAN ACHARJYA]

clc;
clear all;
close all;
n=load('ppg.mat');
ppg=n.data(:,2);
t=(0:(length(ppg)-1));
f_s=1000;
N=length(ppg);
T=[0:N-1]/f_s; %time period(total sample/Fs )
w=50/(f_s/2);
q=34;
bw=w/q;
[b,a]=iirnotch(w,bw); % notch filter implementation 
ppg_f=filter(b,a,ppg);
N1=length(ppg_f);
t1=[0:N1-1]/f_s;
% figure
% plot(ppg_f,'r');              
% xlabel('time')
% ylabel('amplitude')
t = 1:length(ppg_f);
[~,locs_Rwave] = findpeaks(ppg_f,'MinPeakHeight',0.4,'MinPeakDistance',600);
% Remove Edge Wave Data
locs_Rwave(locs_Rwave < 150 | locs_Rwave > (length(ppg_f) - 150)) = [];
x=locs_Rwave.';
frecventainstantanee=ones(1,length(x));
timpobataie=ones(1,length(x)-1);
deltaT=ones(1,length(x)-1); 
r=length(x);  
 for o=1:r-1
     for j=1:r-1
       %while(o<r )
         deltaT(j)=x(o+1)-x(o);                                  
     end
 end

[Cristina Soltoianu]

Thank you very much, KALYAN ACHARJYA, I will try it right away.