mirror of
https://github.com/levinsv/pgadmin3.git
synced 2026-05-15 14:15:49 -06:00
93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
|
|
/*
|
|
* M_APM - mapm_lg4.c
|
|
*
|
|
* Copyright (C) 2003 - 2007 Michael C. Ring
|
|
*
|
|
* Permission to use, copy, and distribute this software and its
|
|
* documentation for any purpose with or without fee is hereby granted,
|
|
* provided that the above copyright notice appear in all copies and
|
|
* that both that copyright notice and this permission notice appear
|
|
* in supporting documentation.
|
|
*
|
|
* Permission to modify the software is granted. Permission to distribute
|
|
* the modified code is granted. Modifications are to be distributed by
|
|
* using the file 'license.txt' as a template to modify the file header.
|
|
* 'license.txt' is available in the official MAPM distribution.
|
|
*
|
|
* This software is provided "as is" without express or implied warranty.
|
|
*/
|
|
|
|
/*
|
|
*
|
|
* This file contains the LOG_NEAR_1 function.
|
|
*
|
|
*/
|
|
|
|
#include "pgAdmin3.h"
|
|
#include "pgscript/utilities/mapm-lib/m_apm_lc.h"
|
|
|
|
/****************************************************************************/
|
|
/*
|
|
calculate log (1 + x) with the following series:
|
|
|
|
x
|
|
y = ----- ( |y| < 1 )
|
|
x + 2
|
|
|
|
|
|
[ 1 + y ] y^3 y^5 y^7
|
|
log [-------] = 2 * [ y + --- + --- + --- ... ]
|
|
[ 1 - y ] 3 5 7
|
|
|
|
*/
|
|
void M_log_near_1(M_APM rr, int places, M_APM xx)
|
|
{
|
|
M_APM tmp0, tmp1, tmp2, tmpS, term;
|
|
int tolerance, dplaces, local_precision;
|
|
long m1;
|
|
|
|
tmp0 = M_get_stack_var();
|
|
tmp1 = M_get_stack_var();
|
|
tmp2 = M_get_stack_var();
|
|
tmpS = M_get_stack_var();
|
|
term = M_get_stack_var();
|
|
|
|
tolerance = xx->m_apm_exponent - (places + 6);
|
|
dplaces = (places + 12) - xx->m_apm_exponent;
|
|
|
|
m_apm_add(tmp0, xx, MM_Two);
|
|
m_apm_divide(tmpS, (dplaces + 6), xx, tmp0);
|
|
|
|
m_apm_copy(term, tmpS);
|
|
m_apm_multiply(tmp0, tmpS, tmpS);
|
|
m_apm_round(tmp2, (dplaces + 6), tmp0);
|
|
|
|
m1 = 3L;
|
|
|
|
while (TRUE)
|
|
{
|
|
m_apm_multiply(tmp0, term, tmp2);
|
|
|
|
if ((tmp0->m_apm_exponent < tolerance) || (tmp0->m_apm_sign == 0))
|
|
break;
|
|
|
|
local_precision = dplaces + tmp0->m_apm_exponent;
|
|
|
|
if (local_precision < 20)
|
|
local_precision = 20;
|
|
|
|
m_apm_set_long(tmp1, m1);
|
|
m_apm_round(term, local_precision, tmp0);
|
|
m_apm_divide(tmp0, local_precision, term, tmp1);
|
|
m_apm_add(tmp1, tmpS, tmp0);
|
|
m_apm_copy(tmpS, tmp1);
|
|
m1 += 2;
|
|
}
|
|
|
|
m_apm_multiply(tmp0, MM_Two, tmpS);
|
|
m_apm_round(rr, places, tmp0);
|
|
|
|
M_restore_stack(5); /* restore the 5 locals we used here */
|
|
}
|
|
/****************************************************************************/
|