Re: Simulation: digital vs analogue

On Saturday 26 January 2008 15:10, Tim Tyler wrote:
``We should keep in mind as well that you digital computing
can be functionally equivalent to analog computing - that
is we can perform any of the functions of a hybrid
digital-analog network with an all digital computer.
The reverse is not true: we can't simulate all of the
functions of the digital computer with an analogue one.''

- The Singularity is Near, Ray Kurzweil, page 130

What?!?

Both can do universal computation - and so can simulate
any other type of system with an arbitrary degree of
precision.

True analog computation doesn't have an arbitrary degree of
precision.

A slide rule is an analog computer which can multiply two
numbers. It is limited to three, maybe four significant
figures. A digital computer are routinely programmed to
multiply number thousands of digits long, for example in
encryption schemes. Even a rigid slide rule the size of
the galaxy with atomic resolution could only manage about
35 digits of accuracy.

-paul-

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