Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
    Re: An OCR attempt of the "Table de Point Miniature" article.
    From: Robert Pearson
    Date: 2017 Mar 30, 10:57 -0700

    Tony,

    The delta value at 0° appears to me to be adjusted so a better value for the cosine can be calculated between angle of 0° and 0°.5. You can calculate a delta value for 0.25° which to 1 decimal is 0.1 x10e-5. and maybe that's what he used. In any case I think this recognizes that a delta of 0.0 while correct for 0° does not provisde a way to calculate a "good" value for angles between 0° and 0°.5.

    At 0°.5 I calculate a delta of 0.3 (0.2581) and from Doniol I read 0.2. This might imply he used some value between 0°.25 and 0°.5 to calculate the delta.  Again without comparing values calculated using the table against more accurate values I can't say whether this provides better interpolated values under some metric. But the purpose of the delta is to facilitate interpolation within the table and to that end using a delta value based exactly on the entry value is not appropriate at angles near 0° for the cosine (or near 90° for the sine).

    The rest of the tabular values agree very well with calculations I made in open office calc. To you comment about values at 61°, I read a value of 0.48481 (looks more like 0.48181 at 1st glance but obviously a problem with scanning) for the cosine and for the delta 25.4, both values match the values I calculated in the spreadsheet I set up.

    I do agree a better scanned copy might help here.

    Robert Pearson

    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