constants.h

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00001 /* -*- C++ -*- ------------------------------------------------------------
00002  
00003 Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
00004 
00005 The Configurable Math Library (CML) is distributed under the terms of the
00006 Boost Software License, v1.0 (see cml/LICENSE for details).
00007 
00008  *-----------------------------------------------------------------------*/
00013 #ifndef cml_constants_h
00014 #define cml_constants_h
00015 
00016 #include <cmath>
00017 
00018 #if !defined(M_PI)
00019 #define M_PI 3.14159265358979323846264338327950288
00020 #endif
00021 
00022 #if !defined(M_SQRT2)
00023 #define M_SQRT2 1.41421356237309504880168872420969808
00024 #endif
00025 
00026 #if !defined(M_E)
00027 #define M_E 2.71828182845904523536028747135266250
00028 #endif
00029 
00030 namespace cml {
00031 
00032 #if 1
00033 
00038 template<typename Float>
00039 struct constants {
00040     static Float pi()          { return Float(M_PI); }
00041     static Float two_pi()      { return Float(2.*M_PI); }
00042     static Float inv_pi()      { return Float(1./M_PI); }
00043     static Float inv_two_pi()  { return Float(1./(2.*M_PI)); }
00044     static Float pi_over_2()   { return Float(M_PI/2.); }
00045     static Float pi_over_4()   { return Float(M_PI/4.); }
00046     static Float deg_per_rad() { return Float(180./M_PI); }
00047     static Float rad_per_deg() { return Float(M_PI/180.); }
00048 
00049     static Float sqrt_2() { return Float(M_SQRT2); }
00050     static Float sqrt_3() { return Float(1.732050807568877293527446341505); }
00051     static Float sqrt_5() { return Float(2.236067977499789696409173668731); }
00052     static Float sqrt_6() { return Float(2.449489742783178098197284074705); }
00053 
00054     static Float e() { return Float(M_E); }
00055 };
00056 
00057 #else
00058 
00059 /* XXX This version requires an explicit instantiation of *every* constant
00060  * below, e.g.:
00061  *
00062  * template<typename F> const F cml::constants<F>::pi;
00063  */
00068 template<typename Float>
00069 struct constants {
00070     static const Float pi = M_PI;
00071     static const Float two_pi = 2.*M_PI;
00072     static const Float inv_pi = 1./M_PI;                /* 1/pi */
00073     static const Float inv_two_pi = 1./(2.*M_PI);       /* 1/(2*pi) */
00074     static const Float pi_over_2 = M_PI/2.;             /* pi/2 */
00075     static const Float pi_over_4 = M_PI/4.;             /* pi/4 */
00076     static const Float deg_per_rad = 180./M_PI;
00077     static const Float rad_per_deg = M_PI/180.;
00078     static const Float sqrt_2 = M_SQRT2;
00079     static const Float sqrt_3 = 1.73205080756887729352744634150587237;
00080     static const Float sqrt_5 = 2.23606797749978969640917366873127624;
00081     static const Float sqrt_6 = 2.44948974278317809819728407470589139;
00082     static const Float e = M_E;
00083 };
00084 
00085 #endif
00086 
00087 } // namespace cml
00088 
00089 #endif