Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Logarithms: adding ten
    From: Frank Reed
    Date: 2019 May 11, 08:40 -0700

    They were simply called logarithms, and this trick of adding ten to logs of trig functions to avoid negative values (both because subtraction is difficult and also because it's easier to tabulate and print all positive values) was just "normal work" with "common logarithms". You had titled this thread "19th Century Logarithms". I changed it because this practice of adding ten to log trig tables was common and standard right through the end of the era, even in the 1960s. 

    More generally:
    You don't need more obfuscatory jargon. They're logarithms. Plain and simple. Even some of the "named" logarithms, like the infamous "proportional logarithms" which have confused and needlessly obsessed so many students of lunars, are merely logarithms with un-necessary jargon labels attached. Jargon doesn't help. :)

    Frank Reed

    PS: You wrote: "adding 10 to a log is adding 10^10 or 10,000,000,000 to the common number". Obviously you merely mis-spoke there, but in case anyone with less background in this old-timey logarithmic math is puzzled here, adding 10 to a logarithm is equivalent to multiplying the original number by 1010 (or ten billion). It's a handy trick.

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site