Bioequivalence and Bioavailability Forum

ln vs. log [RSABE / ABEL]

posted by Helmut  – Vienna, Austria, 2010-11-09 23:07 (5711 d 19:13 ago) – Posting: # 6130
Views: 17,699

Lá maith, Angus!

❝ At highschool in the UK [...] the term "log" pertained to a logarithm to the base 10.

❝ Now for a log to the base e (otherwise known as a natural logarithm or Napierian logarithm) we were taught to use the term "ln". They were first used by John Napier, who was a Scottish mathematician (late 17^th century).

Yeah! I guess you’re still a patriot – even after your move to the former colonies!

BTW, in my posts I’ve used ln rather than log in order to avoid any ambiguities (see also the label of the y-axis in my second plot above). I guess Detlew used log assuming to be evident from the following exp which kind is meant. In SAS and R/S+ log() calls the natural logarithm – so we might be excused.

Since I was trained as a chemical engineer, I’m used to switch my brain. In mechanical engineering and (in-)organic technology we used solely log₁₀, because it’s easy to guess a value from the part before the decimal point: a log₁₀ of 3.69897 means something between 10³ and 10⁴. Only an idiot savant can tell 10^3.69897=5000… In physical chemistry we used mainly ln; like in PK solving systems of differential equations is much easier in the ‘world’ of e. Well known exceptions in chemistry, where the decadic log is used are pK-values. Neutral pH means –log₁₀([H₃O⁺])=7 or 10^-7 molar H₃O⁺.

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна! 
Helmut Schütz


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Science Quotes

Complete thread:

• reference scaled bioequivalence AngusMcLean 2010-11-07 14:55 
  • reference scaled bioequivalence Helmut 2010-11-07 16:08
    • reference scaled bioequivalence AngusMcLean 2010-11-08 22:22
      • RSABE: FDA vs. EMA Helmut 2010-11-09 02:13
        • Farside CV relabelling d_labes 2010-11-09 10:42
          • Farside CV relabelling Helmut 2010-11-09 15:10
            • Laszlo's constant d_labes 2010-11-09 16:46
          • Farside CV relabelling AngusMcLean 2010-11-09 17:12
            • Widened calculations step by step d_labes 2010-11-09 19:48
              • Widened calculations step by step AngusMcLean 2010-11-09 20:46
                • ln vs. logHelmut 2010-11-09 22:07
                • ln on US calculators! d_labes 2010-11-10 08:31
                  • Spreadsheet addiction Helmut 2010-11-10 13:42
            • CV vs. sigma Helmut 2010-11-09 20:11
              • CV vs. sigma AngusMcLean 2010-11-09 20:57
                • log(e) vs. log(10) Helmut 2010-11-09 21:31
              • slide 15 of the Pharsight presentation SDavis 2010-11-19 18:02
        • one more ref. for the ref. list of RSABE yjlee168 2010-11-30 07:16
          • Great! Helmut 2010-11-30 15:44