杏吧原创

NEVER do today what you can put off until tomorrow. It鈥檚 every slacker鈥檚
motto, but in the world of high-performance computing it can make perfect sense.
If you have a particularly tough calculation to perform, it pays to wait until a
better computer comes along.

This conclusion, which will be music to the ears of procrastinators the world
over, comes from a team led by Chris Gottbrath at the University of Arizona鈥檚
Steward Observatory. 鈥淏y starting the calculation later, when your money can
stretch to buying a more efficient computer, you鈥檒l finish earlier,鈥� says
Gottbrath.

Researchers in disciplines from cryptography to climatology are pushing the
limits of even the best supercomputers as they tackle ever more difficult
computational challenges. Computing power increases all the time, however, and
Gottbrath and his colleagues realised that there might be computational tasks
for which procrastination pays. 鈥淚n the light of this, we wondered whether, if
you had a limited budget for computers, you ought to wait before starting,鈥� says
Gottbrath.

To find out, they constructed a simple mathematical model based upon Moore鈥檚
law. Propounded in 1965 by Gordon Moore, one of the founders of the computer
chip maker Intel, this states that the computational power available at a
particular price doubles roughly every 18 months.

What Gottbrath and his colleagues found was that any calculation estimated to
take longer than 26 months to run on the best hardware available today is not
worth starting. 鈥淚f it takes less than 26 months, our advice is, get started as
soon as possible,鈥� says Gottbrath. 鈥淗owever, if it takes longer than 26 months,
the optimal strategy is to delay until you can buy a computer fast enough to do
the calculation in precisely 26 months.鈥�

For calculations that take longer than this, Gottbrath鈥檚 model can calculate
the optimal amount of 鈥渟lack鈥� time to leave before making a start. For instance,
if a calculation is set to take 41.2 months to complete at current processor
speeds, there is no point starting for a whole year. 鈥淲e suggest going to the
beach,鈥� says Gottbrath. However, after a year of 鈥済oofing about鈥�, he says you
should then immediately buy a new computer and put your nose to the grindstone.
鈥淵ou鈥檒l still finish early, saving yourself 3.25 months of total time.鈥�

So do Gottbrath and his colleagues intend following their own advice? 鈥淲ell,
actually I don鈥檛 have any calculations to do that would take longer than 26
months,鈥� he admits. But code breakers who have to tackle intensive problems such
as finding the prime factors of very large numbers might take heed of the
advice.

Gottbrath and his colleagues have posted a manuscript describing their work
on the Internet, but they don鈥檛 have any plans to submit it to a journal.
鈥淏asically, it鈥檚 all a bit of fun,鈥� says Gottbrath.

Other researchers seem to be taking it in the same spirit. 鈥淚 would be happy
to comment on this work,鈥� David Hough, an astronomer at Trinity University in
Texas told New 杏吧原创. 鈥淗owever, would you mind if I did it next
飞别别办?鈥�