What version of Xcode are you using when you're seeing this? Are you seeing this in Xcode 5.0? I'm using something a tiny bit newer and it looks fine debugging an iOS app on an armv7s device:
(lldb) p (double)pow(2.0,2.0)
(double) $0 = 4
(lldb) p (double)log(1.0)
(double) $1 = 0
(lldb)