Source code of Windows XP (NT5)
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//-----------------------------------------------------------------------------
// Package Title ratpak
// File itransh.c
// Author Timothy David Corrie Jr. ([email protected])
// Copyright (C) 1995-97 Microsoft
// Date 01-16-95
//
//
// Description
//
// Contains inverse hyperbolic sin, cos, and tan functions.
//
// Special Information
//
//
//-----------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if defined( DOS )
#include <dosstub.h>
#else
#include <windows.h>
#endif
#include <ratpak.h>
//-----------------------------------------------------------------------------
//
// FUNCTION: asinhrat
//
// ARGUMENTS: x PRAT representation of number to take the inverse
// hyperbolic sine of
// RETURN: asinh of x in PRAT form.
//
// EXPLANATION: This uses Taylor series
//
// n
// ___ 2 2
// \ ] -(2j+1) X
// \ thisterm ; where thisterm = thisterm * ---------
// / j j+1 j (2j+2)*(2j+3)
// /__]
// j=0
//
// thisterm = X ; and stop when thisterm < precision used.
// 0 n
//
// For abs(x) < .85, and
//
// asinh(x) = log(x+sqrt(x^2+1))
//
// For abs(x) >= .85
//
//-----------------------------------------------------------------------------
void asinhrat( PRAT *px )
{
PRAT neg_pt_eight_five = NULL;
DUPRAT(neg_pt_eight_five,pt_eight_five);
neg_pt_eight_five->pp->sign *= -1;
if ( rat_gt( *px, pt_eight_five) || rat_lt( *px, neg_pt_eight_five) )
{
PRAT ptmp = NULL;
DUPRAT(ptmp,(*px));
mulrat(&ptmp,*px);
addrat(&ptmp,rat_one);
rootrat(&ptmp,rat_two);
addrat(px,ptmp);
lograt(px);
destroyrat(ptmp);
}
else
{
CREATETAYLOR();
xx->pp->sign *= -1;
DUPRAT(pret,(*px));
DUPRAT(thisterm,(*px));
DUPNUM(n2,num_one);
do
{
NEXTTERM(xx,MULNUM(n2) MULNUM(n2)
INC(n2) DIVNUM(n2) INC(n2) DIVNUM(n2));
}
while ( !SMALL_ENOUGH_RAT( thisterm ) );
DESTROYTAYLOR();
}
destroyrat(neg_pt_eight_five);
}
//-----------------------------------------------------------------------------
//
// FUNCTION: acoshrat
//
// ARGUMENTS: x PRAT representation of number to take the inverse
// hyperbolic cose of
// RETURN: acosh of x in PRAT form.
//
// EXPLANATION: This uses
//
// acosh(x)=ln(x+sqrt(x^2-1))
//
// For x >= 1
//
//-----------------------------------------------------------------------------
void acoshrat( PRAT *px )
{
if ( rat_lt( *px, rat_one ) )
{
throw CALC_E_DOMAIN;
}
else
{
PRAT ptmp = NULL;
DUPRAT(ptmp,(*px));
mulrat(&ptmp,*px);
subrat(&ptmp,rat_one);
rootrat(&ptmp,rat_two);
addrat(px,ptmp);
lograt(px);
destroyrat(ptmp);
}
}
//-----------------------------------------------------------------------------
//
// FUNCTION: atanhrat
//
// ARGUMENTS: x PRAT representation of number to take the inverse
// hyperbolic tangent of
//
// RETURN: atanh of x in PRAT form.
//
// EXPLANATION: This uses
//
// 1 x+1
// atanh(x) = -*ln(----)
// 2 x-1
//
//-----------------------------------------------------------------------------
void atanhrat( PRAT *px )
{
PRAT ptmp = NULL;
DUPRAT(ptmp,(*px));
subrat(&ptmp,rat_one);
addrat(px,rat_one);
divrat(px,ptmp);
(*px)->pp->sign *= -1;
lograt(px);
divrat(px,rat_two);
destroyrat(ptmp);
}