X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Finifcns_gamma.cpp;h=46c8ea9e00e717652b188a0979f18224bc639fa0;hp=0ae8d1a351c985effbcd5cc95b2f891651e25b5c;hb=94ead6345f31939c9c9eff70ce88d74cf36a8004;hpb=c767dce21baae973b3787497584d8780c56d69d2 diff --git a/ginac/inifcns_gamma.cpp b/ginac/inifcns_gamma.cpp index 0ae8d1a3..46c8ea9e 100644 --- a/ginac/inifcns_gamma.cpp +++ b/ginac/inifcns_gamma.cpp @@ -4,7 +4,7 @@ * some related stuff. */ /* - * GiNaC Copyright (C) 1999-2004 Johannes Gutenberg University Mainz, Germany + * GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -18,12 +18,9 @@ * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ -#include -#include - #include "inifcns.h" #include "constant.h" #include "pseries.h" @@ -35,6 +32,9 @@ #include "symmetry.h" #include "utils.h" +#include +#include + namespace GiNaC { ////////// @@ -54,8 +54,7 @@ static ex lgamma_evalf(const ex & x) /** Evaluation of lgamma(x), the natural logarithm of the Gamma function. - * Knows about integer arguments and that's it. Somebody ought to provide - * some good numerical evaluation some day... + * Handles integer arguments as a special case. * * @exception GiNaC::pole_error("lgamma_eval(): logarithmic pole",0) */ static ex lgamma_eval(const ex & x) @@ -69,7 +68,8 @@ static ex lgamma_eval(const ex & x) else throw (pole_error("lgamma_eval(): logarithmic pole",0)); } - // lgamma_evalf should be called here once it becomes available + if (!ex_to(x).is_rational()) + return lgamma(ex_to(x)); } return lgamma(x).hold(); @@ -110,10 +110,26 @@ static ex lgamma_series(const ex & arg, } +static ex lgamma_conjugate(const ex & x) +{ + // conjugate(lgamma(x))==lgamma(conjugate(x)) unless on the branch cut + // which runs along the negative real axis. + if (x.info(info_flags::positive)) { + return lgamma(x); + } + if (is_exactly_a(x) && + !x.imag_part().is_zero()) { + return lgamma(x.conjugate()); + } + return conjugate_function(lgamma(x)).hold(); +} + + REGISTER_FUNCTION(lgamma, eval_func(lgamma_eval). evalf_func(lgamma_evalf). derivative_func(lgamma_deriv). series_func(lgamma_series). + conjugate_func(lgamma_conjugate). latex_name("\\log \\Gamma")); @@ -142,11 +158,11 @@ static ex tgamma_eval(const ex & x) { if (x.info(info_flags::numeric)) { // trap integer arguments: - const numeric two_x = _num2*ex_to(x); + const numeric two_x = (*_num2_p)*ex_to(x); if (two_x.is_even()) { // tgamma(n) -> (n-1)! for postitive n if (two_x.is_positive()) { - return factorial(ex_to(x).sub(_num1)); + return factorial(ex_to(x).sub(*_num1_p)); } else { throw (pole_error("tgamma_eval(): simple pole",1)); } @@ -156,16 +172,17 @@ static ex tgamma_eval(const ex & x) // trap positive x==(n+1/2) // tgamma(n+1/2) -> Pi^(1/2)*(1*3*..*(2*n-1))/(2^n) if (two_x.is_positive()) { - const numeric n = ex_to(x).sub(_num1_2); - return (doublefactorial(n.mul(_num2).sub(_num1)).div(pow(_num2,n))) * sqrt(Pi); + const numeric n = ex_to(x).sub(*_num1_2_p); + return (doublefactorial(n.mul(*_num2_p).sub(*_num1_p)).div(pow(*_num2_p,n))) * sqrt(Pi); } else { // trap negative x==(-n+1/2) // tgamma(-n+1/2) -> Pi^(1/2)*(-2)^n/(1*3*..*(2*n-1)) - const numeric n = abs(ex_to(x).sub(_num1_2)); - return (pow(_num_2, n).div(doublefactorial(n.mul(_num2).sub(_num1))))*sqrt(Pi); + const numeric n = abs(ex_to(x).sub(*_num1_2_p)); + return (pow(*_num_2_p, n).div(doublefactorial(n.mul(*_num2_p).sub(*_num1_p))))*sqrt(Pi); } } - // tgamma_evalf should be called here once it becomes available + if (!ex_to(x).is_rational()) + return tgamma(ex_to(x)); } return tgamma(x).hold(); @@ -206,10 +223,18 @@ static ex tgamma_series(const ex & arg, } +static ex tgamma_conjugate(const ex & x) +{ + // conjugate(tgamma(x))==tgamma(conjugate(x)) + return tgamma(x.conjugate()); +} + + REGISTER_FUNCTION(tgamma, eval_func(tgamma_eval). evalf_func(tgamma_evalf). derivative_func(tgamma_deriv). series_func(tgamma_series). + conjugate_func(tgamma_conjugate). latex_name("\\Gamma")); @@ -221,7 +246,7 @@ static ex beta_evalf(const ex & x, const ex & y) { if (is_exactly_a(x) && is_exactly_a(y)) { try { - return tgamma(ex_to(x))*tgamma(ex_to(y))/tgamma(ex_to(x+y)); + return exp(lgamma(ex_to(x))+lgamma(ex_to(y))-lgamma(ex_to(x+y))); } catch (const dunno &e) { } } @@ -245,13 +270,13 @@ static ex beta_eval(const ex & x, const ex & y) ny.is_real() && ny.is_integer()) { if (nx.is_negative()) { if (nx<=-ny) - return pow(_num_1, ny)*beta(1-x-y, y); + return pow(*_num_1_p, ny)*beta(1-x-y, y); else throw (pole_error("beta_eval(): simple pole",1)); } if (ny.is_negative()) { if (ny<=-nx) - return pow(_num_1, nx)*beta(1-y-x, x); + return pow(*_num_1_p, nx)*beta(1-y-x, x); else throw (pole_error("beta_eval(): simple pole",1)); } @@ -262,7 +287,8 @@ static ex beta_eval(const ex & x, const ex & y) (nx+ny).is_integer() && !(nx+ny).is_positive()) return _ex0; - // beta_evalf should be called here once it becomes available + if (!ex_to(x).is_rational() || !ex_to(x).is_rational()) + return evalf(beta(x, y).hold()); } return beta(x,y).hold(); @@ -326,8 +352,8 @@ REGISTER_FUNCTION(beta, eval_func(beta_eval). evalf_func(beta_evalf). derivative_func(beta_deriv). series_func(beta_series). - latex_name("\\mbox{B}"). - set_symmetry(sy_symm(0, 1))); + latex_name("\\mathrm{B}"). + set_symmetry(sy_symm(0, 1))); ////////// @@ -356,7 +382,7 @@ static ex psi1_eval(const ex & x) if (nx.is_positive()) { // psi(n) -> 1 + 1/2 +...+ 1/(n-1) - Euler numeric rat = 0; - for (numeric i(nx+_num_1); i>0; --i) + for (numeric i(nx+(*_num_1_p)); i>0; --i) rat += i.inverse(); return rat-Euler; } else { @@ -364,13 +390,13 @@ static ex psi1_eval(const ex & x) throw (pole_error("psi_eval(): simple pole",1)); } } - if ((_num2*nx).is_integer()) { + if (((*_num2_p)*nx).is_integer()) { // half integer case if (nx.is_positive()) { // psi((2m+1)/2) -> 2/(2m+1) + 2/2m +...+ 2/1 - Euler - 2log(2) numeric rat = 0; - for (numeric i = (nx+_num_1)*_num2; i>0; i-=_num2) - rat += _num2*i.inverse(); + for (numeric i = (nx+(*_num_1_p))*(*_num2_p); i>0; i-=(*_num2_p)) + rat += (*_num2_p)*i.inverse(); return rat-Euler-_ex2*log(_ex2); } else { // use the recurrence relation @@ -380,7 +406,7 @@ static ex psi1_eval(const ex & x) // where r == ((-1/2)^(-1) + ... + (-m-1/2)^(-1)) numeric recur = 0; for (numeric p = nx; p<0; ++p) - recur -= pow(p, _num_1); + recur -= pow(p, *_num_1_p); return recur+psi(_ex1_2); } } @@ -423,7 +449,7 @@ static ex psi1_series(const ex & arg, } unsigned psi1_SERIAL::serial = - function::register_new(function_options("psi"). + function::register_new(function_options("psi", 1). eval_func(psi1_eval). evalf_func(psi1_evalf). derivative_func(psi1_deriv). @@ -462,9 +488,9 @@ static ex psi2_eval(const ex & n, const ex & x) const numeric &nx = ex_to(x); if (nx.is_integer()) { // integer case - if (nx.is_equal(_num1)) + if (nx.is_equal(*_num1_p)) // use psi(n,1) == (-)^(n+1) * n! * zeta(n+1) - return pow(_num_1,nn+_num1)*factorial(nn)*zeta(ex(nn+_num1)); + return pow(*_num_1_p,nn+(*_num1_p))*factorial(nn)*zeta(ex(nn+(*_num1_p))); if (nx.is_positive()) { // use the recurrence relation // psi(n,m) == psi(n,m+1) - (-)^n * n! / m^(n+1) @@ -473,25 +499,25 @@ static ex psi2_eval(const ex & n, const ex & x) // where r == (-)^n * n! * (1^(-n-1) + ... + (m-1)^(-n-1)) numeric recur = 0; for (numeric p = 1; p