natural logarithm(redirected from ln)
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a logarithm whose base is the number e = 2.71828 .... The first tables of natural logarithms of numbers from 1 to 1,000 were published by the British mathematician J. Speidell in New Logarithmes (1619). The name “natural logarithm” is due to the German scientist N. Mercator (1668). The natural logarithm of the number N is denoted by In N.