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+power_law(1) -- Sample N integers from a discrete power-law distribution
+======
+
+## SYNOPSIS
+
+`power_law` <gamma> <k_min> <k_max> <N> 
+
+## DESCRIPTION
+
+`power_law` samples <N> elements from the discrete power-law
+distribution 
+
+    P(k) ~ k^{gamma}
+
+where 
+    
+    k_min <= k <= k_max, gamma < 1
+
+The program can be used to generate a power-law degree distribution
+with an assigned value of the exponent <gamma>.
+
+
+## PARAMETERS
+
+* <gamma>:
+    Exponent of the power-law distribution.
+
+* <k_min>, <k_max>:
+    Boundaries of the sampling interval.
+
+* <N> 
+    The number of samples to generate
+
+## OUTPUT
+
+`power_law` prints on the standard output the sampled values, one per
+line, in the format:
+
+    s1
+    s2
+    s3
+     ...
+    sN
+
+The program returns the value `0` if the sum of the samples is even,
+or returns `1` otherwise. The return value can be used to determine
+whether the set of samples can correspond to a degree sequence (if the
+sum of the sequence is odd, then the sequence cannot be a valid degree
+sequence). See [RETURN VALUES][] below.
+
+## EXAMPLES
+
+To generate <N=1000> independent samples from the power-law
+distribution `P(k) ~ k^(-3)`, where samples are in the interval
+`[3, 50]`, we can use:
+
+    $ power_law -3.0 3 50 1000
+    11
+    3
+    3
+    5
+    6
+    7
+     ....
+    8
+    3
+    $
+
+To save the samples in the file `pl_-3.0_3_50_1000`, we redirect STDOUT:
+
+    $ power_law -3.0 3 50 1000 > pl_-3.0_3_50_1000
+
+## RETURN VALUES
+
+The value returned by `power_law ` can be used to test whether the sum
+of the resulting set of samples is even or odd. Under Windows
+PowerShell, you can check the last exit code by inspecting the
+variable `$lastExitCode` right after executing `power_law`, as in:
+    
+    > power_law -2.7 4 300 5000 > pl_-2.7_4_300_5000
+    > $lastExitCode
+    
+    0
+    >
+
+In this case, the exit code is `0`, meaning that the resulting set of
+samples has an even sum (and can be thus used as a degree
+sequence). Under Linux/MacOS/Unix (and in general when using any
+POSIX-compliant shell) you should check the value of the variable
+`$?`, right after executing `power_law`, i.e.:
+
+    $ power_law -2.5 3 500 5000 > pl_-2.5_3_500_5000
+    $ echo $?
+    1
+    $
+
+Notice that this particular run of `power_law` has produced a sequence
+with an odd sum, which thus cannot correspond to a valid degree sequence.
+
+## SEE ALSO
+
+deg_seq(1), conf_model_deg(1), conf_model_deg_nocheck(1)
+
+
+## REFERENCES
+
+* V\. Latora, V. Nicosia, G. Russo, "Complex Networks: Principles,
+  Methods and Applications", Chapter 5, Cambridge University Press
+  (2017)
+
+* V\. Latora, V. Nicosia, G. Russo, "Complex Networks: Principles,
+  Methods and Applications", Appendix 9, Cambridge University Press
+  (2017)
+
+
+## AUTHORS
+
+(c) Vincenzo 'KatolaZ' Nicosia 2009-2017 `<v.nicosia@qmul.ac.uk>`.