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
Having now explained the state of the question, it is time for me to
develope the principle on which is based the construction of this
latter machine. When analysis is employed for the solution of any
problem, there are usually two classes of operations to execute:
firstly, the numerical calculation of the various coefficients; and
secondly, their distribution in relation to the quantities affected by
them. If, for example, we have to obtain the product of two binomials
[Pg 10]
(), the result will be represented by
in which expression we must first calculate ,
, , ; then take the sum of ; and lastly,
respectively distribute the coefficients thus obtained, amongst the
powers of the variable. In order to reproduce these operations by means
of a machine, the latter must therefore possess two distinct sets of
powers: first, that of executing numerical calculations; secondly, that
of rightly distributing the values so obtained.
But if human intervention were necessary for directing each of
these partial operations, nothing would be gained under the heads
of correctness and economy of time; the machine must therefore have
the additional requisite of executing by itself all the successive
operations required for the solution of a problem proposed to it, when
once the primitive numerical data for this same problem have
been introduced. Therefore, since from the moment that the nature of
the calculation to be executed or of the problem to be resolved have
been indicated to it, the machine is, by its own intrinsic power, of
itself to go through all the intermediate operations which lead to the
proposed result, it must exclude all methods of trial and guess-work,
and can only admit the direct processes of calculation[4].
It is necessarily thus; for the machine is not a thinking being, but
simply an automaton which acts according to the laws imposed upon it.
This being fundamental, one of the earliest researches its author had
to undertake, was that of finding means for effecting the division of
one number by another without using the method of guessing indicated
by the usual rules of arithmetic. The difficulties of effecting
this combination were far from being among the least; but upon it
depended the success of every other. Under the impossibility of my
here explaining the process through which this end is attained, we
must limit ourselves to admitting that the four first operations of
arithmetic, that is addition, subtraction, multiplication and division,
can be performed in a direct manner through the intervention of the
machine. This granted, the machine is thence capable of performing
every species of numerical calculation, for all such calculations
ultimately resolve themselves into the four operations we have just
[Pg 11]
named. To conceive how the machine can now go through its functions
according to the laws laid down, we will begin by giving an idea of the
manner in which it materially represents numbers.
Public-domain text, read in full here on John Shaqi.
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