include/siscone/ranlux.h

0001 //! \file ranlux.h
0002
0003 #ifndef __RANLUX_H__
0004 #define __RANLUX_H__
0005
0006 /* This is a lagged fibonacci generator with skipping developed by Luescher.
0007    The sequence is a series of 24-bit integers, x_n,
0008
0009    x_n = d_n + b_n
0010
0011    where d_n = x_{n-10} - x_{n-24} - c_{n-1}, b_n = 0 if d_n >= 0 and
0012    b_n = 2^24 if d_n < 0, c_n = 0 if d_n >= 0 and c_n = 1 if d_n < 0,
0013    where after 24 samples a group of p integers are "skipped", to
0014    reduce correlations. By default p = 199, but can be increased to
0015    365.
0016
0017    The period of the generator is around 10^171.
0018
0019    From: M. Luescher, "A portable high-quality random number generator
0020    for lattice field theory calculations", Computer Physics
0021    Communications, 79 (1994) 100-110.
0022
0023    Available on the net as hep-lat/9309020 at http://xxx.lanl.gov/
0024
0025    See also,
0026
0027    F. James, "RANLUX: A Fortran implementation of the high-quality
0028    pseudo-random number generator of Luscher", Computer Physics
0029    Communications, 79 (1994) 111-114
0030
0031    Kenneth G. Hamilton, F. James, "Acceleration of RANLUX", Computer
0032    Physics Communications, 101 (1997) 241-248
0033
0034    Kenneth G. Hamilton, "Assembler RANLUX for PCs", Computer Physics
0035    Communications, 101 (1997) 249-253  */
0036
0037 namespace siscone{
0038
0039 /// initialize 'ranlux' generator
0040 void ranlux_init();
0041
0042 /// generate random value (24 bits)
0043 unsigned long int ranlux_get();
0044
0045 /// save state of the generator
0046 void ranlux_print_state();
0047
0048 }
0049 #endif