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Good question. It might be because bignum arithmetic in Scheme 48 is
implemented in Scheme. Both elk and scm do it in C. For this kind of thing,
I'd imagine *big* slowdown in moving to byte-codes. However, I'm no expert;
that is really a Scheme 48 question. Try the Scheme 48 mailing list.
One of these days I'm going to implement a cryptography toolkit in
I looked at the core bignum implementation when I saw how slow it was
(many tens of seconds for Diffie-Hellman with a 1024 bit modulus).
It represents bignums in radix 2**14, using lists of fixnums. I think
this gives you a factor-of-six increase in space over a straight bit
Clearly one way to speed it up it would be to rewrite the few critical
inner loops in C or prescheme, using radix 2**16 or 2**32 encoding
within byte strings as the data representation. [The real speed
demons would, of course, want to allow you to replace the inner loop
with hand-tweaked assembler so you can use add-with-carry and
32x32->64 signed multiplies..]
And now for something completely different:
Sometimes I just want to use scheme as a calculator, and see decimals
or scientific notation..
scheme48 (and other schemes in general) seem to go out of their way to
convert things to rationals, which is a great way to avoid loss of
precision, but sometimes you really want to see 4/3 as 1.33333 ...
What's the "right" way to do this in scheme?
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