My first thought would be to try something like this.
Code:
current_height = Get_Analog_Value(rc_ana_in01);
current_height *= .0049;
current_height -= .0044;
current_height = pow(current_height, -1.0895);
current_height *= 29.401;
Working with floats can be very confusing, since the default casting is (int). I always like to try it like this, until I'm sure my logic is correct. In fact, this may even result in less assembly instructions, although I'm not sure at all.