#smoothing filter
L= filt;
a=1;
b=1/(L)*ones(1,L);

kdc = sum(b) / sum(a);
si = fliplr(cumsum(fliplr(b - kdc * a)));

#test
#rpmvalues=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]

# if 'test' = 0 it uses my own filter, 'test' = 1 or 2 are used for comparison
# if = 1 it uses the 'filter' function (the function used inside filtfilt), so this is only forward filtering
# if = 2 it uses the 'filtfilt' function
test = 0;
if(test==0)
  lrefl = 3 * (L - 1);
  v = [2*rpmvalues(1)-rpmvalues((lrefl+1):-1:2), rpmvalues ,2*rpmvalues(end)-rpmvalues((end-1):-1:end-lrefl)];
  z = zeros(1,length(v)+1);
  k=1;
  while(k<=L)
    z(k)=si(k);
    k+=1;
  endwhile
  z(1)=[];
  #forward filter
  #si(1) = [];
  #rpmfiltered = filter(b,a,v,si*v(1));

  rpmfiltered = zeros(1,length(rpmvalues));
  m=1;
  while(m<=length(v))
    i=1;
    summation=0;
    while(i<=L&&m-i+1>=1)
      summation += b(i)*v(m-i+1);
      i+=1;
    endwhile
    rpmfiltered(m) = summation + z(m-i+2);
    m+=1;
  endwhile
  #reverse filter

  rpmfiltered = fliplr(rpmfiltered);
  m=1;
  while(m<=length(rpmfiltered))
    i=1;
    summation=0;
    while(i<=L&&m-i+1>=1)
      summation += b(i)*rpmfiltered(m-i+1);
      i+=1;
    endwhile
    rpmfiltered(m) = summation + z(m-i+2);
    m+=1;
  endwhile
  rpmfiltered = fliplr(rpmfiltered);

  rpmfiltered = rpmfiltered((lrefl+1):(length(rpmvalues)+lrefl));

elseif(test==1)
  si(1) = [];
  rpmfiltered = filter(b,a,rpmvalues,si);
elseif(test==2)
  rpmfiltered=filtfilt(b,a,rpmvalues);
endif