298 lines
11 KiB
C++
298 lines
11 KiB
C++
// Copyright 2011 John Maddock. Distributed under the Boost
|
|
// Distributed under the Boost Software License, Version 1.0.
|
|
// (See accompanying file LICENSE_1_0.txt or copy at
|
|
// http://www.boost.org/LICENSE_1_0.txt)
|
|
//
|
|
// This file has no include guards or namespaces - it's expanded inline inside default_ops.hpp
|
|
//
|
|
|
|
template <class T>
|
|
void calc_log2(T& num, unsigned digits)
|
|
{
|
|
typedef typename boost::multiprecision::detail::canonical<boost::uint32_t, T>::type ui_type;
|
|
typedef typename mpl::front<typename T::signed_types>::type si_type;
|
|
|
|
//
|
|
// String value with 1100 digits:
|
|
//
|
|
static const char* string_val = "0."
|
|
"6931471805599453094172321214581765680755001343602552541206800094933936219696947156058633269964186875"
|
|
"4200148102057068573368552023575813055703267075163507596193072757082837143519030703862389167347112335"
|
|
"0115364497955239120475172681574932065155524734139525882950453007095326366642654104239157814952043740"
|
|
"4303855008019441706416715186447128399681717845469570262716310645461502572074024816377733896385506952"
|
|
"6066834113727387372292895649354702576265209885969320196505855476470330679365443254763274495125040606"
|
|
"9438147104689946506220167720424524529612687946546193165174681392672504103802546259656869144192871608"
|
|
"2938031727143677826548775664850856740776484514644399404614226031930967354025744460703080960850474866"
|
|
"3852313818167675143866747664789088143714198549423151997354880375165861275352916610007105355824987941"
|
|
"4729509293113897155998205654392871700072180857610252368892132449713893203784393530887748259701715591"
|
|
"0708823683627589842589185353024363421436706118923678919237231467232172053401649256872747782344535347"
|
|
"6481149418642386776774406069562657379600867076257199184734022651462837904883062033061144630073719489";
|
|
//
|
|
// Check if we can just construct from string:
|
|
//
|
|
if(digits < 3640) // 3640 binary digits ~ 1100 decimal digits
|
|
{
|
|
num = string_val;
|
|
return;
|
|
}
|
|
//
|
|
// We calculate log2 from using the formula:
|
|
//
|
|
// ln(2) = 3/4 SUM[n>=0] ((-1)^n * N!^2 / (2^n(2n+1)!))
|
|
//
|
|
// Numerator and denominator are calculated separately and then
|
|
// divided at the end, we also precalculate the terms up to n = 5
|
|
// since these fit in a 32-bit integer anyway.
|
|
//
|
|
// See Gourdon, X., and Sebah, P. The logarithmic constant: log 2, Jan. 2004.
|
|
// Also http://www.mpfr.org/algorithms.pdf.
|
|
//
|
|
num = static_cast<ui_type>(1180509120uL);
|
|
T denom, next_term, temp;
|
|
denom = static_cast<ui_type>(1277337600uL);
|
|
next_term = static_cast<ui_type>(120uL);
|
|
si_type sign = -1;
|
|
|
|
ui_type limit = digits / 3 + 1;
|
|
|
|
for(ui_type n = 6; n < limit; ++n)
|
|
{
|
|
temp = static_cast<ui_type>(2);
|
|
eval_multiply(temp, ui_type(2 * n));
|
|
eval_multiply(temp, ui_type(2 * n + 1));
|
|
eval_multiply(num, temp);
|
|
eval_multiply(denom, temp);
|
|
sign = -sign;
|
|
eval_multiply(next_term, n);
|
|
eval_multiply(temp, next_term, next_term);
|
|
if(sign < 0)
|
|
temp.negate();
|
|
eval_add(num, temp);
|
|
}
|
|
eval_multiply(denom, ui_type(4));
|
|
eval_multiply(num, ui_type(3));
|
|
INSTRUMENT_BACKEND(denom);
|
|
INSTRUMENT_BACKEND(num);
|
|
eval_divide(num, denom);
|
|
INSTRUMENT_BACKEND(num);
|
|
}
|
|
|
|
template <class T>
|
|
void calc_e(T& result, unsigned digits)
|
|
{
|
|
typedef typename mpl::front<typename T::unsigned_types>::type ui_type;
|
|
//
|
|
// 1100 digits in string form:
|
|
//
|
|
const char* string_val = "2."
|
|
"7182818284590452353602874713526624977572470936999595749669676277240766303535475945713821785251664274"
|
|
"2746639193200305992181741359662904357290033429526059563073813232862794349076323382988075319525101901"
|
|
"1573834187930702154089149934884167509244761460668082264800168477411853742345442437107539077744992069"
|
|
"5517027618386062613313845830007520449338265602976067371132007093287091274437470472306969772093101416"
|
|
"9283681902551510865746377211125238978442505695369677078544996996794686445490598793163688923009879312"
|
|
"7736178215424999229576351482208269895193668033182528869398496465105820939239829488793320362509443117"
|
|
"3012381970684161403970198376793206832823764648042953118023287825098194558153017567173613320698112509"
|
|
"9618188159304169035159888851934580727386673858942287922849989208680582574927961048419844436346324496"
|
|
"8487560233624827041978623209002160990235304369941849146314093431738143640546253152096183690888707016"
|
|
"7683964243781405927145635490613031072085103837505101157477041718986106873969655212671546889570350354"
|
|
"0212340784981933432106817012100562788023519303322474501585390473041995777709350366041699732972508869";
|
|
//
|
|
// Check if we can just construct from string:
|
|
//
|
|
if(digits < 3640) // 3640 binary digits ~ 1100 decimal digits
|
|
{
|
|
result = string_val;
|
|
return;
|
|
}
|
|
|
|
T lim;
|
|
lim = ui_type(1);
|
|
eval_ldexp(lim, lim, digits);
|
|
|
|
//
|
|
// Standard evaluation from the definition of e: http://functions.wolfram.com/Constants/E/02/
|
|
//
|
|
result = ui_type(2);
|
|
T denom;
|
|
denom = ui_type(1);
|
|
ui_type i = 2;
|
|
do{
|
|
eval_multiply(denom, i);
|
|
eval_multiply(result, i);
|
|
eval_add(result, ui_type(1));
|
|
++i;
|
|
}while(denom.compare(lim) <= 0);
|
|
eval_divide(result, denom);
|
|
}
|
|
|
|
template <class T>
|
|
void calc_pi(T& result, unsigned digits)
|
|
{
|
|
typedef typename mpl::front<typename T::unsigned_types>::type ui_type;
|
|
typedef typename mpl::front<typename T::float_types>::type real_type;
|
|
//
|
|
// 1100 digits in string form:
|
|
//
|
|
const char* string_val = "3."
|
|
"1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679"
|
|
"8214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196"
|
|
"4428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273"
|
|
"7245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094"
|
|
"3305727036575959195309218611738193261179310511854807446237996274956735188575272489122793818301194912"
|
|
"9833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132"
|
|
"0005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235"
|
|
"4201995611212902196086403441815981362977477130996051870721134999999837297804995105973173281609631859"
|
|
"5024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303"
|
|
"5982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989"
|
|
"3809525720106548586327886593615338182796823030195203530185296899577362259941389124972177528347913152";
|
|
//
|
|
// Check if we can just construct from string:
|
|
//
|
|
if(digits < 3640) // 3640 binary digits ~ 1100 decimal digits
|
|
{
|
|
result = string_val;
|
|
return;
|
|
}
|
|
|
|
T a;
|
|
a = ui_type(1);
|
|
T b;
|
|
T A(a);
|
|
T B;
|
|
B = real_type(0.5f);
|
|
T D;
|
|
D = real_type(0.25f);
|
|
|
|
T lim;
|
|
lim = ui_type(1);
|
|
eval_ldexp(lim, lim, -(int)digits);
|
|
|
|
//
|
|
// This algorithm is from:
|
|
// Schonhage, A., Grotefeld, A. F. W., and Vetter, E. Fast Algorithms: A Multitape Turing
|
|
// Machine Implementation. BI Wissenschaftverlag, 1994.
|
|
// Also described in MPFR's algorithm guide: http://www.mpfr.org/algorithms.pdf.
|
|
//
|
|
// Let:
|
|
// a[0] = A[0] = 1
|
|
// B[0] = 1/2
|
|
// D[0] = 1/4
|
|
// Then:
|
|
// S[k+1] = (A[k]+B[k]) / 4
|
|
// b[k] = sqrt(B[k])
|
|
// a[k+1] = a[k]^2
|
|
// B[k+1] = 2(A[k+1]-S[k+1])
|
|
// D[k+1] = D[k] - 2^k(A[k+1]-B[k+1])
|
|
// Stop when |A[k]-B[k]| <= 2^(k-p)
|
|
// and PI = B[k]/D[k]
|
|
|
|
unsigned k = 1;
|
|
|
|
do
|
|
{
|
|
eval_add(result, A, B);
|
|
eval_ldexp(result, result, -2);
|
|
eval_sqrt(b, B);
|
|
eval_add(a, b);
|
|
eval_ldexp(a, a, -1);
|
|
eval_multiply(A, a, a);
|
|
eval_subtract(B, A, result);
|
|
eval_ldexp(B, B, 1);
|
|
eval_subtract(result, A, B);
|
|
bool neg = eval_get_sign(result) < 0;
|
|
if(neg)
|
|
result.negate();
|
|
if(result.compare(lim) <= 0)
|
|
break;
|
|
if(neg)
|
|
result.negate();
|
|
eval_ldexp(result, result, k - 1);
|
|
eval_subtract(D, result);
|
|
++k;
|
|
eval_ldexp(lim, lim, 1);
|
|
}
|
|
while(true);
|
|
|
|
eval_divide(result, B, D);
|
|
}
|
|
|
|
template <class T, const T& (*F)(void)>
|
|
struct constant_initializer
|
|
{
|
|
static void do_nothing()
|
|
{
|
|
init.do_nothing();
|
|
}
|
|
private:
|
|
struct initializer
|
|
{
|
|
initializer()
|
|
{
|
|
F();
|
|
}
|
|
void do_nothing()const{}
|
|
};
|
|
static const initializer init;
|
|
};
|
|
|
|
template <class T, const T& (*F)(void)>
|
|
typename constant_initializer<T, F>::initializer const constant_initializer<T, F>::init;
|
|
|
|
template <class T>
|
|
const T& get_constant_ln2()
|
|
{
|
|
static BOOST_MP_THREAD_LOCAL T result;
|
|
static BOOST_MP_THREAD_LOCAL bool b = false;
|
|
static BOOST_MP_THREAD_LOCAL long digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
if(!b || (digits != boost::multiprecision::detail::digits2<number<T> >::value()))
|
|
{
|
|
calc_log2(result, boost::multiprecision::detail::digits2<number<T, et_on> >::value());
|
|
b = true;
|
|
digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
}
|
|
|
|
constant_initializer<T, &get_constant_ln2<T> >::do_nothing();
|
|
|
|
return result;
|
|
}
|
|
#ifndef BOOST_MP_THREAD_LOCAL
|
|
#error 1
|
|
#endif
|
|
|
|
template <class T>
|
|
const T& get_constant_e()
|
|
{
|
|
static BOOST_MP_THREAD_LOCAL T result;
|
|
static BOOST_MP_THREAD_LOCAL bool b = false;
|
|
static BOOST_MP_THREAD_LOCAL long digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
if(!b || (digits != boost::multiprecision::detail::digits2<number<T> >::value()))
|
|
{
|
|
calc_e(result, boost::multiprecision::detail::digits2<number<T, et_on> >::value());
|
|
b = true;
|
|
digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
}
|
|
|
|
constant_initializer<T, &get_constant_e<T> >::do_nothing();
|
|
|
|
return result;
|
|
}
|
|
|
|
template <class T>
|
|
const T& get_constant_pi()
|
|
{
|
|
static BOOST_MP_THREAD_LOCAL T result;
|
|
static BOOST_MP_THREAD_LOCAL bool b = false;
|
|
static BOOST_MP_THREAD_LOCAL long digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
if(!b || (digits != boost::multiprecision::detail::digits2<number<T> >::value()))
|
|
{
|
|
calc_pi(result, boost::multiprecision::detail::digits2<number<T, et_on> >::value());
|
|
b = true;
|
|
digits = boost::multiprecision::detail::digits2<number<T> >::value();
|
|
}
|
|
|
|
constant_initializer<T, &get_constant_pi<T> >::do_nothing();
|
|
|
|
return result;
|
|
}
|
|
|