On Saturday, 18 October 2014 at 08:21:47 UTC, eles wrote:
On Saturday, 18 October 2014 at 05:54:01 UTC, Ola Fosheim
Grøstad wrote:
On Saturday, 18 October 2014 at 04:35:07 UTC, Walter Bright
wrote:
Larger mantissa can help a little bit, but only a little bit.
https://en.wikipedia.org/wiki/Kahan_summation_algorithm
Kahan helps a little bit:
a = [math.pi*(n**9) for n in range(0,101)]
+[-math.pi*(n**9) for n in range(100,0,-1)]
print sum(a), kahan(a), fsum(a)
-1389.4713685 239.156561184 0.0
but not a lot:
a = [1e16,math.pi,-1e16]
print sum(a), kahan(a), fsum(a)
4.0 4.0 3.14159265359
a = [1e17,math.pi,-1e17]
print sum(a), kahan(a), fsum(a)
0.0 0.0 3.14159265359
