how to resolve "matrix dimension exceeded "error?

please suggest me how to resolve this error in mfcc process-

z=log(H1*(w1(39:K-1)).*conj(w1(39:K-1)));
??? Index exceeds matrix dimensions.

my program is

close all;
clear all;
clc;

%%%%%%%%%%%%%sample read%%%%%%%%%%%%
fs=16000; %sampling frequency, in 1 second take 16000 samples
[s1,f,nbit]=wavread('t on.wav');%read sample 1
[s2,f,nbit]=wavread('t off.wav');%read sample 2
[s3,f,nbit]=wavread('f on.wav');%read sample 3
[s4,f,nbit]=wavread('f off.wav');%read sample 4

%%%%%%%%%%%%%%%%%%%preemphasis%%%%%%%%%%%%%%
B = [1 0.95];
r1 = filter(B,1,s1);
r2 = filter(B,1,s2);
r3 = filter(B,1,s3);
r4 = filter(B,1,s4);

%%%%%%%%%%%%%%windowing,framing and fft%%%%%%%%%%%%
r5=resample(r1,16000,f);
r6=resample(r2,16000,f);
r7=resample(r3,16000,f);
r8=resample(r4,16000,f);
SegmentStep=fs*.02;
noverlap=fs*.025;
framelength=SegmentStep+noverlap ;
nfft=length(r5);
nsegments=floor(nfft/(SegmentStep))-1;
w1=specgram(r5,hamming(framelength),noverlap,nfft,fs);
w2=specgram(r6,hamming(framelength),noverlap,nfft,fs);
w3=specgram(r7,hamming(framelength),noverlap,nfft,fs);
w4=specgram(r8,hamming(framelength),noverlap,nfft,fs);

lfft = 2^12;              % fft size (number of frequency bins)
          K = lfft/2+1;             % length of each filter
          M = 40;                   % number of filters

            hz2mel = @(hz)(1127*log(1+hz/700)); % Hertz to mel warping function
            mel2hz = @(mel)(700*exp(mel/1127)-700); % mel to Hertz warping function

            % Design mel filterbank of M filters each K coefficients long,
            % filters are uniformly spaced on the mel scale between 0 and Fs/2 Hz
            [ H1, freq ] = trifbank( M, K, [300 fs/2], fs, hz2mel, mel2hz );
           figure
            plot( freq, H1 );
            xlabel( 'Frequency (Hz)' ); ylabel( 'Weight' ); set( gca, 'box', 'off' );
            z=log(H1*(w1(40:K)).*conj(w1(40:K)));

please also suggest me next steps to complete this mfcc process

[dpb]

Use code button to format code legibly...

But, set breakpoint and see what are

length(w1)

and

K % ?

K must be <= length(w1)

It appears K will be 2048; too hard to try to parse to figure out what size(w1) might be.