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