Not enough input arguments

Hi! I have written a function for rpeakdetect of an ECG signal and when I run the code return with following error Error using rpeakdetect (line 20) Not enough input arguments. here is the entire message code,

 function [hrv, R_t, R_amp, R_index, S_t, S_amp]  = rpeakdetect(data,samp_freq,thresh,testmode)

 %%%%%%%%%%%make threshold default 0.2 -> this was 0.15 on MIT data 
 if nargin < 4
    testmode = 0;
 end
 %%%%%%%%%%%make threshold default 0.2 -> this was 0.15 on MIT data 
 if nargin < 3
    thresh = 0.2;
 end
 %%%%%%%%%%%make sample frequency default 256 Hz 
 if nargin < 2
    samp_freq = 256;
    if(testmode==1)
        fprintf('Assuming sampling frequency of %iHz\n',samp_freq);
    end
 end

 %%%%%%%%%%%check format of data %%%%%%%%%%
 [a b] = size(data);
 if(a>b)
    len =a;
 end
 if(b>a)
    len =b;
 end

 %%%%%%%%%%if there's no time axis - make one 
 if (a | b == 1);
 % make time axis 
    tt = 1/samp_freq:1/samp_freq:ceil(len/samp_freq);
    t = tt(1:len);
    x = data;
 end
 %%%%%%%%%%check if data is in columns or rows
 if (a == 2)  
    x=data(:,1);
    t=data(:,2); 
 end
 if (b == 2)
    t=data(:,1);
    x=data(:,2); 
 end

 %%%%%%%%%bandpass filter data - assume 256hz data %%%%%
  % remove mean
 x = x-mean(x);

 % FIR filtering stage
 bpf=x; %Initialise
 if( (samp_freq==128) & (exist('filterECG128Hz')~=0) )
        bpf = filterECG128Hz(x); 
 end
 if( (samp_freq==256) & (exist('filterECG256Hz')~=0) )
        bpf = filterECG256Hz(x); 
 end

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 %%%%%%%%%differentiate data %%%%%%%%%%%%%%%%%%%%%%%%%%%
 dff = diff(bpf);  % now it's one datum shorter than before

 %%%%%%%%%square data    %%%%%%%%%%%%%%%%%%%%%%%%%%%
 sqr = dff.*dff;   %
 len = len-1; % how long is the new vector now? 

 %%%%%%%%%integrate data over window 'd' %%%%%%%%%%%%%%%%%%%%%%%%%
 d=[1 1 1 1 1 1 1]; % window size - intialise
 if (samp_freq>=256) % adapt for higher sampling rates
   d = [ones(1,round(7*samp_freq/256))]; 
 end
 % integrate
 mdfint = medfilt1(filter(d,1,sqr),10);
 % remove filter delay for scanning back through ECG
 delay = ceil(length(d)/2);
 mdfint = mdfint(delay:length(mdfint));
 %%%%%%%%%segment search area %%%%%%%%%%%%%%%%%%%%%%%
 %%%%first find the highest bumps in the data %%%%%%
 max_h = max (mdfint(round(len/4):round(3*len/4)));

 %%%%then build an array of segments to look in %%%%%
 %thresh = 0.2;
 poss_reg = mdfint>(thresh*max_h);

 %%%%%%%%%and find peaks %%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%find indices into boudaries of each segment %%%
 left  = find(diff([0 poss_reg'])==1); % remember to zero pad at start
 right = find(diff([poss_reg' 0])==-1); % remember to zero pad at end

 %%%%loop through all possibilities  
 for(i=1:length(left))
    [maxval(i) maxloc(i)] = max( bpf(left(i):right(i)) );
    [minval(i) minloc(i)] = min( bpf(left(i):right(i)) );
    maxloc(i) = maxloc(i)-1+left(i); % add offset of present location
    minloc(i) = minloc(i)-1+left(i); % add offset of present location
 end

 R_index = maxloc;
 R_t   = t(maxloc);
 R_amp = maxval;
 S_amp = minval;   %%%%Assuming the S-wave is the lowest
                   %%%%amp in the given window
 S_t   = t(minloc);

 %%%%%%%%%%check for lead inversion %%%%%%%%%%%%%%%%%%%
 % i.e. do minima precede maxima?
 if (minloc(length(minloc))<maxloc(length(minloc))) 
  R_t   = t(minloc);
  R_amp = minval;
  S_t   = t(maxloc);
  S_amp = maxval;
 end

 %%%%%%%%%%%%
 hrv  = diff(R_t);
 resp = R_amp-S_amp; 

 %%%%%%%%%%%%%%%%%%%%
 if (testmode~=0)
 figure(1)
 hold off
 subplot(4,1,1)
 plot(t,x);hold on;plot(t,bpf,'r')
 title('raw ECG (blue) and zero-pahse FIR filtered ECG (red)')
 ylabel('ECG')
 hold off;
 subplot(4,1,2)
 plot(t(1:length(mdfint)),mdfint);hold on;
 %plot(t(1:length(sqr)),sqr);hold on;
 plot(t,max(mdfint)*bpf/(2*max(bpf)),'r')
 plot(t(left),mdfint(left),'og')
 plot(t(right),mdfint(right),'om')
 title('Integrated data with scan boundaries over scaled ECG')
 ylabel('Int ECG')
 hold off;
 subplot(4,1,3)
 plot(t,bpf,'r');hold on;
 plot(R_t,R_amp,'+k');
 plot(S_t,S_amp,'+g');
 title('ECG with R-peaks (black) and S-points (green) over ECG')
 ylabel('ECG+R+S')
 hold off;
 subplot(4,1,4)
 hold off
 plot(R_t(1:length(hrv)),hrv,'r+')
 hold on
 title('RR intervals')
 ylabel('RR (s)')
 hold off
 fprintf('Press any key for next block of data\n');
 pause
 end

please i need help urgently if someone can.

Answer 1

[Steven Lord]

If line 20 is the one that starts " [a b] = size(data);" then you're calling this function with 0 input arguments (either by typing its name in the Command Window or in a function or by pressing the green triangle in the Editor window.) The first time you try to refer to the first input, that input has not yet been defined and so you receive that error.

If you want to guard against this, ERROR if nargin == 0 or use NARGINCHK to do the same thing.

If line 20 is a different line, please format your code and indicate (via a comment) which line is line 20.

[Humaira Batool]

No, sir line 20 is the same as you have recommended. and thank you so much sir for your kind help and advice.