Behind the Notes of Ada Lovelace - Note D

This post will outline the most significant diagram associated with Note D, published by Lovelace.

Note D
The calculations and tabulations that were undergone by the machine consisted of columns of variables. These variables were divided up into three areas:

  1. Variables on which the data is written, these were named "data variables".
  2. Variables that produce the final results, called "result variables".
 3. Variables that receive temporary data for working with, and not actually storing. This is like information stored in a RAM device in a computer today. These were refereed to as "working variables".

Diagram of the Variables used in the Program

Often, the result variables could be like the nature of the working variables. Sometimes a variable which was to receive a result was the recipient of one or more values in the process. Similarly, the data variables became working variables, or result variables, or even both!

In the case of the current equations the three sets of variables remain separate and independent as expected. [1] 

This is an interesting insight to how the first program dealt with the variables in a function. It was not free of crossing over the variables, however as discussed above. It was an incredible approach to tabulating the functions inputted to the Difference and Analytical engines. 

By Sophie Wicks 

References

[1] http://www.fourmilab.ch/babbage/sketch.html