const.py

   1 #-*- coding: utf-8 -*-
   2
   3 from numpy import sqrt, double, power
   4
   5 C = double('3e8')
   6 LY = double('2e-5')
   7 LZ = double('2e-5')
   8 LAMBDA = double('2e-6')
   9
  10 HY = double(1e-7)
  11 HZ = double(1e-7)
  12
  13 def get_characteristic(x):
  14     if not isinstance(x, double):
  15         raise TypeError('argument must be numpy.float64')
  16     else:
  17         s = "%g" % x
  18         l = s.split('e')
  19         return int(l[1])
  20
  21 def timestep(val):
  22     # val = step / (C * sqrt(2))
  23     c = get_characteristic(val)
  24     return power(10, double(c))
  25
  26 HT = timestep(HY)
  27
  28 def test_exp_stable(hy=HY, hz=HZ, ht=HZ, c=C):
  29     gy = (c**2 * ht**2) / (hy**2)
  30     gz = (c**2 * ht**2) / (hz**2)
  31     return (gy + gz < 1)
  32
  33 def test_imp_stable(hy=HY, ht=HT, c=C):
  34     gy = (c**2 * ht**2) / (hy**2)
  35     return (gy <= 1)
  36
  37
  38