Problem with the find function

Hi all,

I have a problem with my code and can't find what's wrong with it. Can someone help me?:(

I'm trying to sum the energy between two indexes,which is the interval of 10s.I use the find function but I get a message error:

??? Improper assignment with rectangular empty matrix.

    Error in ==> testtaux2 at 29
        klow(i)=find (temps >=t2(i),1,'first');

and here is my code:

clear all
close all

data2=load('SML64_long_AE_correct.txt');
data=load('trx9_SML64d_mod3.txt');
%data3=load('count.txt');
%t=data(:,1);
%def=data(:,12);
Q=data(:,11);
Ener=data2(:,14);
temps=data2(:,4);
def=data2(:,7);
defm=data(:,16);
amplitude=data2(:,12);
count=data2(:,9);
cumul_ener=data2(:,17);

dt=10;
k=0;
n=0;
for i=1:length(temps)-dt
    t2(i)=temps(1)+n*dt; 

     t1(i)=t2(i)+dt;
      n=n+1;
      klow(i)=find (temps >=t2(i),1,'first');
      kup(i)=find(temps >t1(i)+2*dt,1,'first');

   dE(i)=sum(Ener((klow(i)):kup(i)));
  t(i)=temps(klow(i))+temps(kup(i))/2;

      k=k+1;
     taux(k)=dE(i)/dt;
     tt(k)=t(i);

end

%file = fopen('tauxfixe.txt','w');  
 % fprintf(file,' %f %f\n',taux(k),tt(k));
 % fclose(file);

figure 
plot(tt,taux)
hold on

Does anyone know what is wrong with my code?

Thank you very much for your help and sorry for my bad English !

Answer 1

[per isakson]

Here are some links on debugging in Matlab

• Debugging in MATLAB
• Debugging session
• Debugging Approaches

Answer 2

[Roger Stafford]

I would guess offhand that when the 'find' function happens to come up empty at

klow(i)=find (temps >=t2(i),1,'first');

then matlab complains about trying to insert an empty array into a single space. If so, you will have to make some special provision for the empty case.

Answer 3

[maxime bernard]

Thank you for your answer. I have tried to change it by replacing the "n" with "kk" index but I still get this messqge error.Do you know whatI can I do it? I have tried so many things and I always this problem.

dt=10;
k=0;

kk=1;
for i=1:length(temps)-dt 

      t1(i)=temps(kk); 
      t2(i)=t1(i)+dt;

      klow(i)=find (temps >=t1(i),1,'first');
      kup(i)=find(temps >t1(i) +dt,1,'first');

     dE(i)=sum(Ener((klow(i)):kup(i)));
     t(i)=temps(klow(i))+temps(kup(i))/2;

kk=kup(i);
   k=k+1;
   taux(k)=dE(i)/dt;
   tt(k)=t(i);

end