Sketch of the Analytical Engine invented by Charles Babbage, Esq.Menabrea, Luigi Federico
Science
Sketch of the Analytical Engine invented by Charles Babbage, Esq.
Menabrea, Luigi Federico
Babbage, Charles, 1791-1871; Numerical analysis
The algebraical nature of the engine (so strongly insisted
on in a previous part of this Note) would enable it to follow out
any of these various modes indifferently; just as we recently showed
that it can distribute and separate the numerical results of any one
prescribed series of processes, in a perfectly arbitrary manner. Were
it otherwise, the engine could merely compute the arithmetical
th function, a result which, like any other purely
arithmetical results, would be simply a collective number, bearing no
traces of the data or the processes which had led to it.
Secondly, the law of development for the th function being
selected, the next step would obviously be to develope (5.) itself,
according to this law. This result would be the first function, and
would be obtained by a determinate series of processes. These in
most cases would include amongst them one or more cycles of
operations.
The third step (which would consist of the various processes necessary
for effecting the actual substitution of the series constituting
the first function, for the variable itself) might
proceed in either of two ways. It might make the substitution either
wherever occurs in the original (5.), or it might similarly make
it wherever occurs in the first function itself which is the
equivalent of (5.). In some cases the former mode might be best, and in
others the latter.
Whichever is adopted, it must be understood that the result is to
appear arranged in a series following the law originally prescribed
for the development of the th function. This result constitutes
the second function; with which we are to proceed exactly as we did
with the first function, in order to obtain the third function; and
so on, times, to obtain the th function. We easily
perceive that since every successive function is arranged in a series
following the same law, there would (after the first
function is obtained) be a cycle, of a cycle, of a cycle,
&c. of operations[27], one, two, three, up to times, in order
to get the th function. We say, after the first function is
obtained, because (for reasons on which we cannot here enter) the
first function might in many cases be developed through a set
[Pg 53]
of processes peculiar to itself, and not recurring for the remaining
functions.
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