Hi, this is a patch to add the base of the natural logarithm as a new constant EulerNum, and ensure that log(EulerNum) evaluates to 1. Of course, exp(1) will do fine for calculations. But for printing, it is nicer to see e^x instead of exp(1)^x or 2.718^x. Hope this is useful. Jan --- ginac/constant.cpp | 5 +++++ ginac/constant.h | 1 + ginac/inifcns_trans.cpp | 3 +++ ginac/numeric.cpp | 5 +++++ ginac/numeric.h | 1 + ginsh/ginsh_lexer.lpp | 1 + 6 files changed, 16 insertions(+) diff --git a/ginac/constant.cpp b/ginac/constant.cpp index a89711ef..60af44bc 100644 --- a/ginac/constant.cpp +++ b/ginac/constant.cpp @@ -91,6 +91,8 @@ void constant::read_archive(const archive_node &n, lst &sym_lst) *this = Catalan; else if (s == Euler.name) *this = Euler; + else if (s == EulerNum.name) + *this = EulerNum; else throw (std::runtime_error("unknown constant '" + s + "' in archive")); } else @@ -254,4 +256,7 @@ const constant Euler("Euler", EulerEvalf, "\\gamma_E", domain::positive); /** Catalan's constant. (0.91597...) Diverts straight into CLN for evalf(). */ const constant Catalan("Catalan", CatalanEvalf, "G", domain::positive); +/** Base of the natural logarithm */ +const constant EulerNum("EulerNum", EulerNumEvalf, "\\mathit{e}", domain::positive); + } // namespace GiNaC diff --git a/ginac/constant.h b/ginac/constant.h index 92d07941..24839d46 100644 --- a/ginac/constant.h +++ b/ginac/constant.h @@ -82,6 +82,7 @@ GINAC_DECLARE_UNARCHIVER(constant); extern const constant Pi; extern const constant Catalan; extern const constant Euler; +extern const constant EulerNum; } // namespace GiNaC diff --git a/ginac/inifcns_trans.cpp b/ginac/inifcns_trans.cpp index 6f577bae..ef5f52f1 100644 --- a/ginac/inifcns_trans.cpp +++ b/ginac/inifcns_trans.cpp @@ -202,6 +202,9 @@ static ex log_eval(const ex & x) return log(ex_to<numeric>(x)); } + if (x.is_equal(EulerNum)) + return *_num1_p; + // log(exp(t)) -> t (if -Pi < t.imag() <= Pi): if (is_ex_the_function(x, exp)) { const ex &t = x.op(0); diff --git a/ginac/numeric.cpp b/ginac/numeric.cpp index 6da79977..addc012d 100644 --- a/ginac/numeric.cpp +++ b/ginac/numeric.cpp @@ -2515,6 +2515,11 @@ ex CatalanEvalf() return numeric(cln::catalanconst(cln::default_float_format)); } +/** Floating point evaluation of base of natural logarithm. */ +ex EulerNumEvalf() +{ + return exp(*_num1_p); // Suggestion by Vladimir Kisil on ginac-devel +} /** _numeric_digits default ctor, checking for singleton invariance. */ _numeric_digits::_numeric_digits() diff --git a/ginac/numeric.h b/ginac/numeric.h index 0673d9a5..d25670f9 100644 --- a/ginac/numeric.h +++ b/ginac/numeric.h @@ -325,6 +325,7 @@ inline const numeric denom(const numeric &x) ex PiEvalf(); ex EulerEvalf(); ex CatalanEvalf(); +ex EulerNumEvalf(); } // namespace GiNaC diff --git a/ginsh/ginsh_lexer.lpp b/ginsh/ginsh_lexer.lpp index 6e0732e7..bcfecd10 100644 --- a/ginsh/ginsh_lexer.lpp +++ b/ginsh/ginsh_lexer.lpp @@ -75,6 +75,7 @@ AN [0-9a-zA-Z_] Pi yylval = Pi; return T_LITERAL; Euler yylval = Euler; return T_LITERAL; Catalan yylval = Catalan; return T_LITERAL; +EulerNum yylval = EulerNum; return T_LITERAL; FAIL yylval = *new fail(); return T_LITERAL; I yylval = I; return T_NUMBER; Digits yylval = (long)Digits; return T_DIGITS; -- 2.43.0