#-----------------------------------------------------------------------------
#
#  Author : philippe.billet@noos.fr
#
#  erfc(x)
#
#  GW  Added erfc() from Numerical Recipes in C
#  
#-----------------------------------------------------------------------------



Eval_erfc = ->
  push(cadr(p1))
  Eval()
  yerfc()

yerfc = ->
  save()
  yyerfc()
  restore()

yyerfc = ->
  d = 0.0

  p1 = pop()

  if (isdouble(p1))
    d = erfc(p1.d)
    push_double(d)
    return

  if isZeroAtomOrTensor(p1)
    push(one)
    return

  push_symbol(ERFC)
  push(p1)
  list(2)
  return

# from Numerical Recipes in C
erfc = (x) ->
  if x == 0
    return 1.0

  t = 0.0
  z = 0.0
  ans = 0.0

  z = Math.abs(x)
  t = 1.0 / (1.0 + 0.5 * z)

  ans=t*Math.exp(-z*z-1.26551223+t*(1.00002368+t*(0.37409196+t*(0.09678418+
  t*(-0.18628806+t*(0.27886807+t*(-1.13520398+t*(1.48851587+
  t*(-0.82215223+t*0.17087277)))))))))

  if x >= 0.0
    return ans
  else
    return 2.0-ans