The exponential and logarithmic function base a and 1/a..
Remark that the exponential and logarithmic function of the same base are symmetric to the bisector line of the first quadrant, y=x. Note the symmetry of the exponential function base a and 1/a related to the y-axis, moreover for the logarithmic function of base a and 1/a related to the x-axis. The complex of the four functions is visualised here and helps studying them.