MATLAB: Error “undefined function or variable ‘y1’ “. Help me please. :\

undefined function or variable

if true
  % code
end--------------------------------start of the code
clc;
clear all;
Fs=8000;
for k=1:30
  clear y1 y2 y3;
display('record voice');
pause();
x=wavrecord(Fs,Fs);
t=0.04;
j=1;
for i=1:8000
  if(abs(x(i))>t)
      y1(j)=x(i);
      j=j+1;
  end
end
y2=y1/(max(abs(y1)));
y3=[y2,zeros(1,3120-length(y2))];
y=filter([1 -0.9],1,y3');%high pass filter to boost the high frequency components
%%frame blocking
blocklen=240;%30ms block
overlap=80;
block(1,:)=y(1:240);
for i=1:18
  block(i+1,:)=y(i*160:(i*160+blocklen-1));
end
w=hamming(blocklen);
for i=1:19
  a=xcorr((block(i,:).*w'),12);%finding auto correlation from lag -12 to 12
  for j=1:12
      auto(j,:)=fliplr(a(j+1:j+12));%forming autocorrelation matrix from lag 0 to 11
  end
  z=fliplr(a(1:12));%forming a column matrix of autocorrelations for lags 1 to 12
  alpha=pinv(auto)*z';
  lpc(:,i)=alpha;
end
wavplay(x,Fs);
X(k,:)=reshape(lpc,1,228);
Y(k,:)=input('enter the number ');
end
save('lpcdata.mat','X','Y');
---------------------------------------the command
record voice
??? Undefined function or variable 'y1'.
Error in ==> normalizedlpc at 17
y2=y1/(max(abs(y1)));

Best Answer

This
j=1;
for i=1:8000
  if(abs(x(i))>t)
      y1(j)=x(i);
      j=j+1;
  end
end
can be vectorized:
y1 = zeros(1, length(x); % Initialize to all zeros.
% Compute logical indexes of where x > t
aboveThreshold = x > t;
if sum(aboveThreshold) > 1
    % At least one element of x is above the threshold.
    % Extract only those above threshold and create a new y1
    % which may be a different length than the initialized one.
    y1 = x(aboveThreshold);
end
but you still might want to find out why no x is above your t threshold, because though my code fixed your code, it will just continue on with a y of all zeros, which is probably useless and not what you want.
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