new_contents: """
     missing data  -s coded as -999 - this filter uses clip to ensure that  the minimum elevation is the value of parameter 0
  
  
  """
  
  import sys, math
  from numpy import *
  
  min_elev = float(sys.argv[1])
  elev = loadtxt(sys.stdin)
  sys.stderr.write("set minimum to "+ str(min_elev)+'\n')
  # replace missing data -9999 by 0 
  clip(elev,min_elev,9999999,elev)
  savetxt(sys.stdout,elev,"%1.2f")
  
subject: Create clip.py