#! /usr/bin/env python # def r8_uniform_ab ( a, b, seed ): #*****************************************************************************80 # ## R8_UNIFORM_AB returns a scaled pseudorandom R8. # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 04 April 2013 # # Author: # # John Burkardt # # Reference: # # Paul Bratley, Bennett Fox, Linus Schrage, # A Guide to Simulation, # Second Edition, # Springer, 1987, # ISBN: 0387964673, # LC: QA76.9.C65.B73. # # Bennett Fox, # Algorithm 647: # Implementation and Relative Efficiency of Quasirandom # Sequence Generators, # ACM Transactions on Mathematical Software, # Volume 12, Number 4, December 1986, pages 362-376. # # Pierre L'Ecuyer, # Random Number Generation, # in Handbook of Simulation, # edited by Jerry Banks, # Wiley, 1998, # ISBN: 0471134031, # LC: T57.62.H37. # # Peter Lewis, Allen Goodman, James Miller, # A Pseudo-Random Number Generator for the System/360, # IBM Systems Journal, # Volume 8, Number 2, 1969, pages 136-143. # # Parameters: # # Input, real A, B, the minimum and maximum values. # # Input, integer SEED, a seed for the random number generator. # # Output, real R, the randomly chosen value. # # Output, integer SEED, an updated seed for the random number generator. # from sys import exit i4_huge = 2147483647 if ( seed == 0 ): print ( '' ) print ( 'R8_UNIFORM_AB - Fatal error!' ) print ( ' Input SEED = 0!' ) exit ( 'R8_UNIFORM_AB - Fatal error!' ) seed = int ( seed ) seed = ( seed % i4_huge ) if ( seed < 0 ): seed = seed + i4_huge k = ( seed // 127773 ) seed = 16807 * ( seed - k * 127773 ) - k * 2836 if ( seed < 0 ): seed = seed + i4_huge r = a + ( b - a ) * seed * 4.656612875E-10 return r, seed def r8_uniform_ab_test ( ): #*****************************************************************************80 # ## R8_UNIFORM_AB_TEST tests R8_UNIFORM_AB. # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 26 July 2014 # # Author: # # John Burkardt # import platform a = 10.0 b = 20.0 print ( '' ) print ( 'R8_UNIFORM_AB_TEST' ) print ( ' Python version: %s' % ( platform.python_version ( ) ) ) print ( ' R8_UNIFORM_AB returns random values in a given range:' ) print ( ' [ A, B ]' ) print ( '' ) print ( ' For this problem:' ) print ( ' A = %f' % ( a ) ) print ( ' B = %f' % ( b ) ) print ( '' ) seed = 123456789 for i in range ( 0, 10 ): r, seed = r8_uniform_ab ( a, b, seed ) print ( ' %f' % ( r ) ) # # Terminate. # print ( '' ) print ( 'R8_UNIFORM_AB_TEST' ) print ( ' Normal end of execution' ) return if ( __name__ == '__main__' ): from timestamp import timestamp timestamp ( ) r8_uniform_ab_test ( ) timestamp ( )