Logarithm

n.
  1. One of a class of auxiliary numbers, devised by John Napier, of Merchiston, Scotland (1550-1617), to abridge arithmetical calculations, by the use of addition and subtraction in place of multiplication and division.
    2. Arithmetical complement of a logarithm ,
    the difference between a logarithm and the number ten.
    Binary logarithms .
    See under Binary.
    Common logarithms, or Brigg's logarithms ,
    logarithms of which the base is 10; -- so called from Henry Briggs, who invented them.
    Gauss's logarithms ,
    tables of logarithms constructed for facilitating the operation of finding the logarithm of the sum of difference of two quantities from the logarithms of the quantities, one entry of those tables and two additions or subtractions answering the purpose of three entries of the common tables and one addition or subtraction. They were suggested by the celebrated German mathematician Karl Friedrich Gauss (died in 1855), and are of great service in many astronomical computations.
    Hyperbolic logarithm or Napierian logarithm or Natural logarithm ,
    a logarithm (devised by John Speidell, 1619) of which the base is e (2.718281828459045...); -- so called from Napier, the inventor of logarithms.
    Logistic logarithms or Proportional logarithms ,
    See under Logistic.