feat(unitproc/python):Add sleepRand.py

- note: sleeps for random amount of time using inverse gaussian
  distribution.

diff --git a/unitproc/python/sleepRand.py b/unitproc/python/sleepRand.py
new file mode 100755 (executable)
index 0000000..76a32e1
--- /dev/null
+++ b/unitproc/python/sleepRand.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# Desc: Pauses a random amount of time. Random distribution is inverse gaussian.
+# Version: 0.0.1
+# Depends: python 3.7.3
+# Usage: ./sleepRand.py arg1
+# Input: arg1: float seconds (mean of inverse gaussian distribution)
+# Example: python3 sleepRand.py 4.0
+
+import math, time, random, sys
+
+# Define functions
+def randInvGau(mu, lam):
+    """Returns random variate of inverse gaussian distribution"""
+    # Ref/Attrib: doi:10.1080/00031305.1976.10479147
+    nu = random.gauss(0,1);
+    y = nu ** 2;
+    xTerm1 = mu;
+    xTerm2 = mu ** 2 * y / (2 * lam);
+    xTerm3 = (- mu / (2 * lam)) * math.sqrt(4 * mu * lam * y + mu ** 2 * y ** 2);
+    x = xTerm1 + xTerm2 + xTerm3;
+    z = random.uniform(0.0,1.0);
+    if z <= (mu / (mu + x)):
+        return x;
+    else:
+        return (mu ** 2 / x);
+
+# Check input (TODO)
+arg1 = float(sys.argv[1]); # first argument
+desMean = arg1;
+
+# Configure
+lambdaFactor = 4; # spread factor; inversely proportional to variance
+
+# Calculate delay
+delay = randInvGau(desMean, desMean * lambdaFactor);
+#print('DEBUG:delay:' + str(float(delay)));
+
+# Sleep
+time.sleep(float(delay));
+
+