Li_eval(): avoid the "numeric::operator>(): complex inequality" exception.

[ginac.git] / ginac / power.cpp

diff --git a/ginac/power.cpp b/ginac/power.cpp
index c6bf7b9770d2fa939eb242fef780f6aa84286dc5..87792b922099215e6b00b9744724eef7ca481ab6 100644 (file)
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -3,7 +3,7 @@
  *  Implementation of GiNaC's symbolic exponentiation (basis^exponent). */
 
 /*
- *  GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2011 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
@@ -242,6 +242,8 @@ bool power::info(unsigned inf) const
                        return (flags & status_flags::expanded);
                case info_flags::positive:
                        return basis.info(info_flags::positive) && exponent.info(info_flags::real);
+               case info_flags::nonnegative:
+                       return basis.info(info_flags::real) && exponent.info(info_flags::integer) && exponent.info(info_flags::even);
                case info_flags::has_indices: {
                        if (flags & status_flags::has_indices)
                                return true;
@@ -362,7 +364,7 @@ ex power::coeff(const ex & s, int n) const
  *  - ^(1,x) -> 1
  *  - ^(c1,c2) -> *(c1^n,c1^(c2-n))  (so that 0<(c2-n)<1, try to evaluate roots, possibly in numerator and denominator of c1)
  *  - ^(^(x,c1),c2) -> ^(x,c1*c2)  if x is positive and c1 is real.
- *  - ^(^(x,c1),c2) -> ^(x,c1*c2)  (c2 integer or -1 < c1 <= 1, case c1=1 should not happen, see below!)
+ *  - ^(^(x,c1),c2) -> ^(x,c1*c2)  (c2 integer or -1 < c1 <= 1 or (c1=-1 and c2>0), case c1=1 should not happen, see below!)
  *  - ^(*(x,y,z),c) -> *(x^c,y^c,z^c)  (if c integer)
  *  - ^(*(x,c1),c2) -> ^(x,c2)*c1^c2  (c1>0)
  *  - ^(*(x,c1),c2) -> ^(-x,c2)*c1^c2  (c1<0)
@@ -480,7 +482,7 @@ ex power::eval(int level) const
                }
        
                // ^(^(x,c1),c2) -> ^(x,c1*c2)
-               // (c1, c2 numeric(), c2 integer or -1 < c1 <= 1,
+               // (c1, c2 numeric(), c2 integer or -1 < c1 <= 1 or (c1=-1 and c2>0),
                // case c1==1 should not happen, see below!)
                if (is_exactly_a<power>(ebasis)) {
                        const power & sub_power = ex_to<power>(ebasis);
@@ -489,7 +491,8 @@ ex power::eval(int level) const
                        if (is_exactly_a<numeric>(sub_exponent)) {
                                const numeric & num_sub_exponent = ex_to<numeric>(sub_exponent);
                                GINAC_ASSERT(num_sub_exponent!=numeric(1));
-                               if (num_exponent->is_integer() || (abs(num_sub_exponent) - (*_num1_p)).is_negative()) {
+                               if (num_exponent->is_integer() || (abs(num_sub_exponent) - (*_num1_p)).is_negative() 
+                                               || (num_sub_exponent == *_num_1_p && num_exponent->is_positive())) {
                                        return power(sub_basis,num_sub_exponent.mul(*num_exponent));
                                }
                        }
@@ -735,8 +738,7 @@ ex power::imag_part() const
        ex b=basis.imag_part();
        ex c=exponent.real_part();
        ex d=exponent.imag_part();
-       return
-               power(abs(basis),c)*exp(-d*atan2(b,a))*sin(c*atan2(b,a)+d*log(abs(basis)));
+       return power(abs(basis),c)*exp(-d*atan2(b,a))*sin(c*atan2(b,a)+d*log(abs(basis)));
 }
 
 // protected