[Paul Moore <[email protected]>]
> ...
> Can you share a bit more about why you need to do this? In the
> abstract, having the ability to split numbers over lines seems
> harmless and occasionally useful, but conversely it's not at all
> obvious why anyone would be doing this in real life.
It's not all that uncommon among people who work in algorithmic number theory.
The P in Steven's example is taken from a paper, where it's the
_input_ to a short calculation that computes Q, a number with about 3
times as many digits. It's Q that's interesting, not really P. By
careful construction, Q is a composite number that fooled many "prime
testing" functions in many popular packages. They claimed Q is
prime(*).
Where did P come from? It's complicated. Far easier to copy/paste
than to compute (for Q, the opposite).
Which, as computational resources grow more capable, becomes more
common: interesting results can be "big" indeed, but computing them
_can_ require CPU-centuries of effort.
That said, while I enjoy playing in that area, I don't have a real
problem with pasting such things in. They're too big to get any
intuitive concept of their size by eyeball, so it's fine by me to
leave them on a single line. Steven's "has 131 digits" comment is far
more informative to me than any way of breaking the literal across
multiple lines.
So I'm -0 on complicating syntax to cater to this. The int(implicitly
pasted string literals) trick has been good enough for me when I've
really wanted it.
(*) For those who care,
Q = P * (313*(P-1) + 1) * (353*(P-1) + 1)
Q is a "Carmichael number", a Fermat pseudoprime to all bases
relatively prime to Q. It's also a strong pseudoprime to all bases <
307, meaning that all Miller-Rabin primality testers that stick to
bases < 307 falsely claim it's prime. And P is Q's smallest prime
factor, so "small to large" trial division is also hopeless for
discovering that Q is composite. Ditto "large to small" trial
division, since Q has no factors anywhere near its square root.
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