source: pcp/src/init.h@ 88e890

#ifndef init_h
#define init_h
/** \file init.h
 * Header file for \ref init.c
 * 
 * Contains declarations of the functions implemented in \ref init.c,
 * enumeration value_type which is needed for ParseForParameters() and
 * one inline function tpow() realising a "x to the power of n" where n
 * may be also arbitrary (also negative) integer.
 * 
  Project: ParallelCarParrinello
  \authors Jan Hamaekers, Frederik Heber
  \date 2000, 2006

  File: init.h
  $Id: init.h,v 1.17 2007/02/09 09:13:48 foo Exp $
*/

// Specifting whether a value in the parameter file must be specified or is optional
enum necessity { optional,    //!< parameter is optional, if not given sensible value is chosen
                 critical     //!< parameter must be given or programme won't initiate
               };

// Specifying the cast type to be read of a parameter, see ParseForParameter()
enum value_type { string_type, double_type, int_type, row_int, row_double, grid, lower_trigrid, upper_trigrid}; 

/* Bereite mainname vor: loescht von filename von rechts nach links bis zu erstem "/" oder ganz */
void CreateMainname(struct Problem *const P, const char* const filename);

/* Einlesen der Parameterdatei */
int ParseForParameter(int verbose, FILE *file, const char *const name, int sequential, int const xth, int const yth, enum value_type type, void *value, int repetition, enum necessity critical);
void ReadParameters(struct Problem *const  P, const char *const filename);
void WriteParameters(struct Problem *const  P, const char *const filename);

void Init(struct Problem *const P);
void InitPerturbation(struct Problem *P);
void InitPsisValue(struct Problem *const P, int start, int end);

/** Calculate the value \a x to the power of \a n.
 * \param x value
 * \param n power
 * \return \f$x^n\f$
 */
static inline double tpow(double x, int n)
{
  double y = 1;
  int neg = (n < 0);

  if (neg) n = -n;

  while (n) {   // go through every bit of the integer number n
    if (n & 1) y *= x;  // if bit set, multiply
    x *= x;   // go to next power of 2
    n >>= 1;   // and to the next bit
  }
  return neg ? 1.0/y : y; // if n was negative, return reciprocal value
}
#endif