 Earlier than Stifel , the 8th century Jain mathematician Virasena is credited with a precursor to the binary logarithm . Virasena 's concept of ardhacheda has been defined as the number of times a given number can be divided evenly by two . This definition gives rise to a function that coincides with the binary logarithm on the powers of two , but it is different for other integers , giving the 2 @-@ adic order rather than the logarithm . 
