function nGauss1d, X, P

  nbP = n_elements(P)
  nbLin = nbP mod 3
  nbGauss = nbP - nbLin
  
;  print, nbP, nbGauss, nbLin

  yMod = x*0.
  for k=0, nbGauss-1 do begin
    ind= k*3 + indgen(3)
    cG = evalGauss( X, p[ind] )
    yMod += cG
  endfor

  indB = nbGauss*3
  indA = indB+1
  case nbLin of
    1: plane = p[indB]
    2: plane = p[indB] + x*p[indA]
    else: plane = x*0

 endcase

  return, (yMod+plane)
END