Transform abs(x)^n => x^n if x is real and n is even.

While at it add some .hold() to returns which cannot be processed further.

Signed-off-by: Vladimir V. Kisil <kisilv@maths.leeds.ac.uk>

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index 9219039a5581df93d58d0c744507ddc4d911a893..8103cd86bf3ec12ad02a2ebec48aff1b122b0c49 100644 (file)
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -212,7 +212,7 @@ static void abs_print_csrc_float(const ex & arg, const print_context & c)
 
 static ex abs_conjugate(const ex & arg)
 {
-       return abs(arg);
+       return abs(arg).hold();
 }
 
 static ex abs_real_part(const ex & arg)
@@ -227,7 +227,8 @@ static ex abs_imag_part(const ex& arg)
 
 static ex abs_power(const ex & arg, const ex & exp)
 {
-       if (arg.is_equal(arg.conjugate()) && is_a<numeric>(exp) && ex_to<numeric>(exp).is_even())
+       if (arg.is_equal(arg.conjugate()) && ((is_a<numeric>(exp) && ex_to<numeric>(exp).is_even())
+                                               || exp.info(info_flags::even)))
                return power(arg, exp);
        else
                return power(abs(arg), exp).hold();
@@ -398,7 +399,7 @@ static ex csgn_power(const ex & arg, const ex & exp)
 {
        if (is_a<numeric>(exp) && exp.info(info_flags::positive) && ex_to<numeric>(exp).is_integer()) {
                if (ex_to<numeric>(exp).is_odd())
-                       return csgn(arg);
+                       return csgn(arg).hold();
                else
                        return power(csgn(arg), _ex2).hold();
        } else
@@ -489,7 +490,7 @@ static ex eta_series(const ex & x, const ex & y,
 
 static ex eta_conjugate(const ex & x, const ex & y)
 {
-       return -eta(x, y);
+       return -eta(x, y).hold();
 }
 
 static ex eta_real_part(const ex & x, const ex & y)
@@ -648,7 +649,7 @@ static ex Li2_conjugate(const ex & x)
        // conjugate(Li2(x))==Li2(conjugate(x)) unless on the branch cuts which
        // run along the positive real axis beginning at 1.
        if (x.info(info_flags::negative)) {
-               return Li2(x);
+               return Li2(x).hold();
        }
        if (is_exactly_a<numeric>(x) &&
            (!x.imag_part().is_zero() || x < *_num1_p)) {
@@ -687,7 +688,7 @@ static ex zetaderiv_eval(const ex & n, const ex & x)
        if (n.info(info_flags::numeric)) {
                // zetaderiv(0,x) -> zeta(x)
                if (n.is_zero())
-                       return zeta(x);
+                       return zeta(x).hold();
        }
        
        return zetaderiv(n, x).hold();