On 9/1/10 4:40 PM, John Bokma wrote:
Arnaud Delobelle<arno...@googlemail.com> writes:
Terry Reedy<tjre...@udel.edu> writes:
But such a document, after stating that array access may be thought of
as constant time on current hardware to a useful first approximation,
should also state that repeated seqeuntial accessess may be *much*
faster than repeated random accessess. People in the high-performance
computing community are quite aware of this difference between
simplified lies and messy truth. Because of this, array algorithms are
(should be) written differently in Fortran and C because Fortran
stores arrays by columns and C by rows and because it is usually much
faster to access the next item than one far away.
I don't understand what you're trying to say. Aahz didn't claim that
random list element access was constant time, he said it was O(1) (and
that it should be part of the Python spec that it is).
Uhm, O(1) /is/ constant time, see page 45 of Introduction to Algorithms,
2nd edition.
While we often use the term "constant time" to as a synonym for O(1) complexity
of an algorithm, Arnaud and Terry are using the term here to mean "an
implementation takes roughly the same amount of wall-clock time every time".
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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