Add the case of c1=-1 and c2>0 to the rewriting rule of exponents: (x^c1)^c2 -> x...

diff --git a/check/exam_powerlaws.cpp b/check/exam_powerlaws.cpp
index cab16dfb5852314e1da23a918bc4eceb738b973a..beb4dfb28d6f4da024b543114ff922f713066fc7 100644 (file)
--- a/check/exam_powerlaws.cpp
+++ b/check/exam_powerlaws.cpp
@@ -69,14 +69,14 @@ static unsigned exam_powerlaws1()
                return 1;
        }
        
-       ex e4 = e1.subs(lst(a==-1, b==2.5));
+       ex e4 = e1.subs(lst(a==-1, b==-2.5));
        if (!(is_exactly_a<power>(e4) &&
              is_exactly_a<power>(e4.op(0)) &&
              is_exactly_a<symbol>(e4.op(0).op(0)) &&
              is_exactly_a<numeric>(e4.op(0).op(1)) &&
              is_exactly_a<numeric>(e4.op(1)) &&
-             e4.is_equal(power(power(x,-1),2.5)) )) {
-               clog << "(x^a)^b, x symbolic, a==-1, b==2.5 wrong" << endl;
+             e4.is_equal(power(power(x,-1),-2.5)) )) {
+               clog << "(x^a)^b, x symbolic, a==-1, b==-2.5 wrong" << endl;
                clog << "returned: " << e4 << endl;
                return 1;
        }

diff --git a/ginac/power.cpp b/ginac/power.cpp
index 9a8f7d5697f46ff00525de25aab94767ab841aaf..b815d17a9e6e07f716748ff909c81dc080835994 100644 (file)
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -362,7 +362,7 @@ 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 +480,7 @@ 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 +489,8 @@ 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));
                                }
                        }