Moved double_exp distn into "distributions.py"

KshitijAggarwal · May 8, 2014 · 6493991 · 6493991
1 parent 0a080a6
commit 6493991
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Showing 2 changed files with 12 additions and 4 deletions.
diff --git a/lib/python/distributions.py b/lib/python/distributions.py
@@ -42,4 +42,12 @@ def draw1d(dist):
  if rand_num <= c:
  return i
 
+def draw_double_sided_exp(scale, origin=0.0):
+ """Exponential distribution around origin, with scale height scale."""
+ if scale == 0.0:
+ return origin
 
+ rn = random.random()
+ sign = random.choice([-1.0, 1.0])
+
+ return origin + sign * scale * math.log(rn)
diff --git a/lib/python/evolve.py b/lib/python/evolve.py
@@ -331,9 +331,9 @@ def birthVelocity( pulsar, pop):
  pulsar.vy = random.gauss(mean, sigma)
  pulsar.vz = random.gauss(mean, sigma)
  elif bvM == 'exp':
- pulsar.vx = go._double_sided_exp(sigma, origin = mean)
- pulsar.vy = go._double_sided_exp(sigma, origin = mean)
- pulsar.vz = go._double_sided_exp(sigma, origin = mean)
+ pulsar.vx = dists.draw_double_sided_exp(sigma, origin = mean)
+ pulsar.vy = dists.draw_double_sided_exp(sigma, origin = mean)
+ pulsar.vz = dists.draw_double_sided_exp(sigma, origin = mean)
  else:
  raise EvolveException('Invalid velocity model selected')
 
@@ -350,7 +350,7 @@ def galacticDistribute(pulsar, pop):
  y = -20. + random.random()*40.
 
  # calculate z and r0
- z = go._double_sided_exp(pop.zscale)
+ z = dists.draw_double_sided_exp(pop.zscale)
  pulsar.galCoords = (x, y, z)
  pulsar.r0 = math.sqrt(x**2 + y**2)