I tried a matlab code for spectral centroid but it showing error like this"Index exceeds matrix dimensions. Error in Untitled2 (line 58) P1i = P2i(1:L/2+1); . How to correct the error?

the code is given below, 
[audio,fs]=audioread('cryrumble.wav');
frameduration=0.25;
frame_len=frameduration*fs;
N=length(audio);
num_frames=floor(N/frame_len);
for k=1:num_frames
    frame=audio( (k-1)*frame_len+1 :frame_len*k);
end

y=fft(frame);

T = 1/fs; % Sampling period

L = length(frame); % Length of signal %%%%% CHANGED %%%%%

t = (0:L-1)*T; % Time vector

P2 = abs(y/L);

P1 = P2(1:L/2+1);

P1(2:end-1) = 2*P1(2:end-1);

f = fs*(0:(L/2))/L;

% Plot overall frequency spectrum %%%%% CHANGED %%%%%

figure

plot(f,P1)

title('Single-Sided Aamplitude Sprecturm for Entire Audio Track')

xlabel('Frequency')

ylabel('Amplitude')

n=250; % length of movin window to calculate spectal centroid in %%%%% CHANGED %%%%%

spec=zeros(1,length(frame)-n); % pre-allocate %%%%% CHANGED %%%%%

fi = Fs*(0:(n/2))/n; % new frequency for fft of length n (Fs doesnt change) %%%%% CHANGED %%%%%

% Loop over audio track with window of length n %%%

for ii=1:length(frame)-n

xi=frame(ii:ii+n-1);

yi=fft(xi);

%%%%% DO THIS %%%%%

% Calculate new "P1i" value based on "yi"
P2i = abs(yi/L);

P1i = P2i(1:L/2+1);

% Use fi and P1i to calculate spec

spec(ii)=sum(fi.*P1i)/sum(P1i);
end

% Plot results

tplot=t(1+round(n/2):L-n+round(n/2)); % center time for spectral centroid window %%%%% CHANGED %%%%%

figure

plot(tplot,spec)

ylabel('Frequency (Hz)')

xlabel('Center of Time Window (seconds)')

Answer 1

[KALYAN ACHARJYA]

Note: The code is tested with different audio file, please check in your case

Line no 28:

Change Fs to fs as Matlab is case sensitive.

Line no 36:

P1i = P2i(1:L/2+1);

Why you getting the error?

whos P2i
  Name      Size             Bytes  Class     Attributes
  P2i       1x250             2000  double     

Here P2i is vector

  P1i = P2i(1:L/2+1);

P2i(any value) represent the index position of that array.

Here you are trying to fing index elemets of a from 1 to L/2+1, L=11025, therefore

>> L/2+1
ans =
   5.5135e+03

Invalid index value,must be positive and real value.

Please find the way out of L/2+1 vlue is positive integer and must be within the range of P2i

Hope it helps!