On 3/20/2011 10:26 PM, bearophile wrote:
dsimcha:
On second thought, given the difficulty finding anything else, rational
may be the thing that's most ready. I'll offer it up for review now
It's good to have rationals in Phobos, thank you.
Is this GCD? There is already a gcd in Phobos. Is this efficient when numbers
gets very large?
CommonInteger!(I1,I2) gcf(I1, I2)(I1 num1, I2 num2);
I knew someone was going to ask this, so I probably should have answered
it pre-emptively. std.numeric.gcd doesn't work with BigInts. I'm
considering making my implementation private and eventually fixing
std.numeric rather than having duplicate public functionality.
An alternative is to give the number of binary digits of precision for the
mantissa (see std.math.feqrel):
Rational!(Int) toRational(Int)(real floatNum, real epsilon = 1e-08);
That's worth considering. The only reason I did it the way I did is
because the Maxima computer algebra system did it this way and, when in
doubt, I generally do what Maxima does in this library. I also think
absolute error is the better metric for this case. If you do:
auto foo = toRational!BigInt(1e-200);
Do we really want to return some ridiculously huge number (that possibly
overflows in the case of fixed width integers) for the denominator in
this case?
