Generates an array of random numbers distributed as a power law.
RANDOMP, X, Pow, N, [ RANGE_X = [low,high], SEED= ]'
Pow: Exponent of power law.
The pdf of X is f_X(x) = A*x^pow, low <= x <= high
ASTRONOMERS PLEASE NOTE:
pow is little gamma = big gamma - 1 for stellar IMFs.
N: Number of elements in generated vector.
Optional Input Keyword Parameter
RANGE_X: 2-element vector [low,high] specifying the range of
output X values; the default is [5, 100].
OPTIONAL INPUT-OUTPUT KEYWORD PARAMETER:
SEED: Seed value for RANDOMU function. As described in the
documentation for RANDOMU, the value of SEED is updated on
each call to RANDOMP, and taken from the system clock if not
supplied. This keyword can be used to have RANDOMP give
identical results on different runs.
X: Vector of random numbers, distributed as a power law between
"Transformation Method" for random variables is described in Bevington
& Robinson, "Data Reduction & Error Analysis for Physical Sciences", 2nd
Edition (McGraw-Hill, 1992). p. 83.
Output of RANDOMU function is transformed to power-law
Create a stellar initial mass function (IMF) with 10000 stars
ranging from 0.5 to 100 solar masses and a Salpeter slope. Enter:
Versions 5.1.1 and V5.2 of IDL have a bug in RANDOMU such that the SEED
value is initialized to the same value at the start of each session,
rather than being initialized by the system clock. RANDOMP will be
affected in a similar manner.
Written by R. S. Hill, Hughes STX, July 13, 1995
July 14, 1995 SEED keyword added at Landsman's suggestion.
Documentation converted to standard format. RSH
Converted to IDL V5.0 W. Landsman September 1997