gnucash/src/engine/gnc-numeric.h

/********************************************************************
 * gnc-numeric.h -- an exact-number library for gnucash.            *
 * Copyright (C) 2000 Bill Gribble                                  *
 *                                                                  *
 * This program is free software; you can redistribute it and/or    *
 * modify it under the terms of the GNU General Public License as   *
 * published by the Free Software Foundation; either version 2 of   *
 * the License, or (at your option) any later version.              *
 *                                                                  *
 * This program is distributed in the hope that it will be useful,  *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of   *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    *
 * GNU General Public License for more details.                     *
 *                                                                  *
 * You should have received a copy of the GNU General Public License*
 * along with this program; if not, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 59 Temple Place - Suite 330        Fax:    +1-617-542-2652       *
 * Boston, MA  02111-1307,  USA       gnu@gnu.org                   *
 *                                                                  *
 *******************************************************************/

/** @file gnc-numeric.h @brief An exact-number library for gnucash.*/

#ifndef GNC_NUMERIC_H
#define GNC_NUMERIC_H

#include <glib.h>

struct _gnc_numeric {
  gint64  num;
  gint64  denom;
};

/** @brief An exact-number type for gnucash. 
 *
 * This is a rational number, defined by nominator and denominator. */
typedef struct _gnc_numeric gnc_numeric;

/** bitmasks for HOW flags */
#define GNC_NUMERIC_RND_MASK     0x0000000f
#define GNC_NUMERIC_DENOM_MASK   0x000000f0
#define GNC_NUMERIC_SIGFIGS_MASK 0x0000ff00

/** rounding/truncation modes for operations */
enum { 
  GNC_RND_FLOOR            = 0x01, 
  GNC_RND_CEIL             = 0x02,  
  GNC_RND_TRUNC            = 0x03,
  GNC_RND_PROMOTE          = 0x04,
  GNC_RND_ROUND_HALF_DOWN  = 0x05, 
  GNC_RND_ROUND_HALF_UP    = 0x06, 
  GNC_RND_ROUND            = 0x07, 
  GNC_RND_NEVER            = 0x08
};

/** auto-denominator types */
enum { 
  GNC_DENOM_EXACT  = 0x10, 
  GNC_DENOM_REDUCE = 0x20,
  GNC_DENOM_LCD    = 0x30,
  GNC_DENOM_FIXED  = 0x40,
  GNC_DENOM_SIGFIG = 0x50
};

/** bits 8-15 of 'how' are reserved for the number of significant
 * digits to use in the output with GNC_DENOM_SIGFIG */ 

/** errors */
enum {
  GNC_ERROR_OK         =  0,
  GNC_ERROR_ARG        = -1,
  GNC_ERROR_OVERFLOW   = -2,
  GNC_ERROR_DENOM_DIFF = -3,
  GNC_ERROR_REMAINDER  = -4
};

#define GNC_DENOM_AUTO 0

#define GNC_DENOM_RECIPROCAL( a ) (- ( a ))
#define GNC_DENOM_SIGFIGS( a ) ( ((( a ) & 0xff) << 8) | GNC_DENOM_SIGFIG)
#define GNC_NUMERIC_GET_SIGFIGS( a ) ( (( a ) & 0xff00 ) >> 8)

/** @name Constructors */
/*@{*/
/** make a gnc_numeric from numerator and denominator */
gnc_numeric gnc_numeric_create(gint64 num, gint64 denom);

/** create a zero-value gnc_numeric */
gnc_numeric gnc_numeric_zero(void);

/** convert from floating-point values */
gnc_numeric double_to_gnc_numeric(double in, gint64 denom,  
                                  gint how);

/** Read a gnc_numeric from str, skipping any leading whitespace, and
   returning a pointer to just past the last byte read.  Return NULL
   on error. */
const gchar *string_to_gnc_numeric(const gchar* str, gnc_numeric *n);

/** make a special error-signalling gnc_numeric */
gnc_numeric gnc_numeric_error(int error_code);
/*@}*/

/** @name Value accessors */
/*@{*/
/** Get parts */
gint64 gnc_numeric_num(gnc_numeric a);
/** Get parts */
gint64 gnc_numeric_denom(gnc_numeric a);

/** Convert to floating-point values */
double      gnc_numeric_to_double(gnc_numeric in);

/** Convert to string. The returned buffer is to be g_free'd by the
 * caller (it was allocated through g_strdup) */
gchar *gnc_numeric_to_string(gnc_numeric n);
/*@}*/

/** @name Tests */
/*@{*/
/** Check for error signal in value. Returns GNC_ERROR_OK (==0) if
 * there is no error, or any error code if there is one
 * (e.g. GNC_ERROR_OVERFLOW) */ 
int         gnc_numeric_check(gnc_numeric a);

/** Returns 1 if the given gnc_numeric is 0 (zeros), else returns 0. */
int gnc_numeric_zero_p(gnc_numeric a);                
/** Returns 1 if a>b, -1 if b>a, 0 if a == b  */
int gnc_numeric_compare(gnc_numeric a, gnc_numeric b);
int gnc_numeric_negative_p(gnc_numeric a);
int gnc_numeric_positive_p(gnc_numeric a);

/** Equivalence predicate: Returns TRUE (1) if a and b are exactly the
 * same (same numerator and denominator)
 */ 
int gnc_numeric_eq(gnc_numeric a, gnc_numeric b);     
/** Equivalence predicate: Returns TRUE (1) if a and b represent
 *  exactly the same number (ratio of numerator to denominator is
 *  exactly equal)
 */ 
int gnc_numeric_equal(gnc_numeric a, gnc_numeric b);  
/** Equivalence predicate: Returns TRUE (1) if after both are
 * converted to DENOM using method HOW, a and b are
 * gnc_numeric_equal().
 */ 
int gnc_numeric_same(gnc_numeric a, gnc_numeric b,   
                     gint64 denom, gint how);
/*@}*/

/** @name Arithmetic operations */
/*@{*/
gnc_numeric gnc_numeric_add(gnc_numeric a, gnc_numeric b, 
                            gint64 denom, gint how);
gnc_numeric gnc_numeric_sub(gnc_numeric a, gnc_numeric b, 
                            gint64 denom, gint how);
gnc_numeric gnc_numeric_mul(gnc_numeric a, gnc_numeric b, 
                            gint64 denom, gint how);
gnc_numeric gnc_numeric_div(gnc_numeric a, gnc_numeric b, 
                            gint64 denom, gint how);
/** Negate the argument  */
gnc_numeric gnc_numeric_neg(gnc_numeric a);
/** Return the absolute value of the argument */
gnc_numeric gnc_numeric_abs(gnc_numeric a);

/** Shortcut for common operations */
gnc_numeric gnc_numeric_add_fixed(gnc_numeric a, gnc_numeric b);
/** Shortcut for common operations */
gnc_numeric gnc_numeric_sub_fixed(gnc_numeric a, gnc_numeric b);
/*@}*/

/** @name Arithmetic functions with exact error returns */
/*@{*/
gnc_numeric gnc_numeric_add_with_error(gnc_numeric a, gnc_numeric b,
                                       gint64 denom, gint how,
                                       gnc_numeric * error);
gnc_numeric gnc_numeric_sub_with_error(gnc_numeric a, gnc_numeric b,
                                       gint64 denom, gint how,
                                       gnc_numeric * error);
gnc_numeric gnc_numeric_mul_with_error(gnc_numeric a, gnc_numeric b,
                                       gint64 denom, gint how,
                                       gnc_numeric * error);
gnc_numeric gnc_numeric_div_with_error(gnc_numeric a, gnc_numeric b,
                                       gint64 denom, gint how,
                                       gnc_numeric * error);
/*@}*/

/** @name Change denominator */
/*@{*/
/** change the denominator of a gnc_numeric value */
gnc_numeric gnc_numeric_convert(gnc_numeric in, gint64 denom, 
                                gint how);

/** change the denominator of a gnc_numeric value */
gnc_numeric gnc_numeric_convert_with_error(gnc_numeric in, gint64 denom, 
                                           gint how,
                                           gnc_numeric * error);

/** reduce by GCF elimination */
gnc_numeric gnc_numeric_reduce(gnc_numeric in);
/*@}*/


#endif