EXPRESS 1.0b2 FTF Avatar
  1. OMG Issue

EXPRESS — EXPRESS MM issue: Correct definition of E

  • Key: EXPRESS-6
  • Legacy Issue Number: 14071
  • Status: closed  
  • Source: THALES ( Hugues Vincent)
  • Summary:

    Clause 9.8.2 I don't know what the "Napierian exponential function" is. Perhaps it is more usual to native English speaker? Yet I didn't find anything worthwhile when I googlized it (is Google anyway a reference?). I just know the "exponential function" and the "naperian logarithm function" which is the inverse of the preceding.
    Yet defining e from one of these functions whose definitions are, AFAIK, based on e itself doesn't make sense.
    I'd recommand to use the original Euler's definition: see
    If agreed, that could be handled through an issue for the 2nd FTF.

  • Reported: EXPRESS 1.0b1 — Tue, 23 Jun 2009 04:00 GMT
  • Disposition: Resolved — EXPRESS 1.0b2
  • Disposition Summary:

    The definition of E in the specification was taken verbatim from ISO 10303-11 Clause 14.2. However, the issue is correct: Napier published a table of natural logarithms, but the exponential function is credited to Euler. The specification should use one of Euler's definition (based on the area under the curve 1/x), or Bernoulli's definition (the limit of (1+1/n)n).

  • Updated: Fri, 6 Mar 2015 20:58 GMT