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Added comments explaining reasons for macro format.

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[SVN r3601]
This commit is contained in:
Paul A. Bristow
2007-01-05 12:31:40 +00:00
parent 9a59557542
commit 4ccf8a528f
1 changed files with 15 additions and 1 deletions
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16
include/boost/math/constants/constants.hpp
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@@ -21,6 +21,20 @@ namespace boost{ namespace math
{
namespace constants
{
// To permit other calculations at about 100 decimal digits with NTL::RR type,
// it is obviously necessary to define constants to this accuracy.
// However, some compilers do not accept decimal digits strings as long as this.
// So the constant is split into two parts, with the 1st containing at least
// long double precision, and the 2nd zero if not needed or known.
// The 3rd part permits an exponent to be provided if necessary (use zero if none) -
// the other two parameters may only contain decimal digits (and sign and decimal point),
// and may NOT include an exponent like 1.234E99.
// The second digit string is only used if T is a User-Defined Type,
// when the constant is converted to a long string literal and lexical_casted to type T.
// (This is necessary because you can't use a numeric constant
// since even a long double might not have enough digits).
#define BOOST_DEFINE_MATH_CONSTANT(name, x, y, exp)\
template <class T> inline T name(BOOST_EXPLICIT_TEMPLATE_TYPE(T))\
@@ -36,7 +50,7 @@ namespace boost{ namespace math
{ return BOOST_JOIN(BOOST_JOIN(x, BOOST_JOIN(e, exp)), L); }
BOOST_DEFINE_MATH_CONSTANT(pi, 3.141592653589793238462643383279502884197169399375105820974944, 59230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196, 0)
BOOST_DEFINE_MATH_CONSTANT(root_pi, 1.7724538509055160272981674833411451827975, , 0)
BOOST_DEFINE_MATH_CONSTANT(root_pi, 1.7724538509055160272981674833411451827975, 0, 0)
BOOST_DEFINE_MATH_CONSTANT(root_half_pi, 1.253314137315500251207882642405522626503, 0, 0)
BOOST_DEFINE_MATH_CONSTANT(root_two_pi, 2.506628274631000502415765284811045253007, 0, 0)
BOOST_DEFINE_MATH_CONSTANT(root_ln_four, 1.1774100225154746910115693264596996377473856893858205385225257565000, 2658854698492680841813836877081, 0)