Bug in power::derivative.

diff --git a/ginac/power.cpp b/ginac/power.cpp
index 1e9b6849e88cf40f8900e7d7ba1b42cf0f073bcc..cd72a629be7b10a3d2c40888d8d182ad357b9aea 100644 (file)
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -583,7 +583,7 @@ ex power::conjugate() const
  *  @see ex::diff */
 ex power::derivative(const symbol & s) const
 {
-       if (exponent.info(info_flags::real)) {
+       if (is_a<numeric>(exponent)) {
                // D(b^r) = r * b^(r-1) * D(b) (faster than the formula below)
                epvector newseq;
                newseq.reserve(2);