include/random.h

   1 /*
   2  * $Id$
   3  *
   4  *                This source code is part of
   5  *
   6  *                 G   R   O   M   A   C   S
   7  *
   8  *          GROningen MAchine for Chemical Simulations
   9  *
  10  *                        VERSION 3.1
  11  * Copyright (c) 1991-2001, University of Groningen, The Netherlands
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * If you want to redistribute modifications, please consider that
  18  * scientific software is very special. Version control is crucial -
  19  * bugs must be traceable. We will be happy to consider code for
  20  * inclusion in the official distribution, but derived work must not
  21  * be called official GROMACS. Details are found in the README & COPYING
  22  * files - if they are missing, get the official version at www.gromacs.org.
  23  *
  24  * To help us fund GROMACS development, we humbly ask that you cite
  25  * the papers on the package - you can find them in the top README file.
  26  *
  27  * For more info, check our website at http://www.gromacs.org
  28  *
  29  * And Hey:
  30  * Getting the Right Output Means no Artefacts in Calculating Stuff
  31  */
  32
  33 #ifndef _random_h
  34 #define _random_h
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include <config.h>
  38 #endif
  39
  40 #include <typedefs.h>
  41
  42
  43 typedef struct t_gaussdata *t_Gaussdata;
  44 /* Abstract data type for the internal state of
  45  * a gaussian random number generator
  46  */
  47
  48 t_Gaussdata init_gauss(int seed);
  49 /* Initialize (and warm up) a gaussian random number generator
  50  * by copying the seed. The routine returns a handle to the
  51  * new generator.
  52  */
  53
  54 real
  55 gauss(t_Gaussdata data);
  56 /* Return a new gaussian random number with expectation value
  57  * 0.0 and standard deviation 1.0. This routine is NOT thread-safe
  58  * for performance reasons - you will either have to do the locking
  59  * yourself, or better: initialize one generator per thread.
  60  */
  61
  62 void
  63 finish_gauss(t_Gaussdata data);
  64 /* Release all the resources used for the generator */
  65
  66
  67
  68
  69 extern int make_seed(void);
  70 /* Make a random seed: (time+getpid) % 1000000 */
  71
  72 extern real rando(int *seed);
  73 /* Generate a random number 0 <= r < 1. seed is the (address of) the
  74  * random seed variable.
  75  */
  76
  77 extern void grp_maxwell(t_block *grp,real tempi[],int nrdf[],int seed,
  78                         t_atoms *atoms,rvec v[]);
  79 /* Generate for each group in grp a temperature.
  80  * When seed = -1, set the seed to make_seed.
  81  */
  82
  83 extern void maxwell_speed(real tempi,int nrdf,int seed,
  84                           t_atoms *atoms, rvec v[]);
  85 /* Generate velocites according to a maxwellian distribution */
  86
  87 extern real calc_cm(FILE *log,int natoms,real mass[],rvec x[],rvec v[],
  88                     rvec xcm,rvec vcm,rvec acm,matrix L);
  89 /* Calculate the c.o.m. position, velocity, acceleration and the
  90  * moment of Inertia. Returns the total mass.
  91  */
  92
  93 extern void stop_cm(FILE *log,int natoms,real mass[],rvec x[],rvec v[]);
  94
  95 #endif  /* _random_h */