Donald Knuth once wrote these unfortunate words:
” We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.”
This statement is often quoted in an attempt to de-emphasize code performance in favor of other factors which are considered more important:
- Ease of use
- Rapid development
- Clarity and readability
- Reusability
- Risk of accidental bugs
- Extensibility
- Elegance
- Object-Oriented Purity
.. The irony about Knuth’s quote is that the people who most often quote it would be horrified by its original context. Knuth made this statement in an article in which he argued in favor of the careful use of go-to statements for micro-optimization in performance-intensive loops
.. The improvement in speed from Example 2 to Example 2a is only about 12%, and many people would pronounce that insignificant. The conventional wisdom shared by many of today’s software engineers calls for ignoring efficiency in the small; but I believe this is simply an overreaction to the abuses they see being practiced by penny-wise- and-pound-foolish programmers, who can’t debug or maintain their “optimized” programs. In established engineering disciplines a 12% improvement, easily obtained, is never considered marginal; and I believe the same viewpoint should prevail in software engineering. Of course I wouldn’t bother making such optimizations on a one-shot job, but when it’s a question of preparing quality programs, I don’t want to restrict myself to tools that deny me such efficiencies.
.. As software engineers, we have largely forgotten about our obligation to create quality programs where efficiency is concerned. We have built for ourselves a culture in which constant factors are the compiler’s problem and the hardware’s problem, in which our productivity, comfort, and profit are more important than the effective utilization of the user’s resources, and the quality of their experience under load.
Donald Knuth Quotes
The psychological profiling [of a programmer] is mostly the ability to shift levels of abstraction, from low level to high level. To see something in the small and to see something in the large.
.. The important thing, once you have enough to eat and a nice house, is what you can do for others, what you can contribute to the enterprise as a whole.
.. The whole thing that makes a mathematician’s life worthwhile is that he gets the grudging admiration of three or four colleagues.
.. A mathematical formula should never be “owned” by anybody! Mathematics belong to God.
.. Email is a wonderful thing for people whose role in life is to be on top of things. But not for me; my role is to be on the bottom of things. What I do takes long hours of studying and uninterruptible concentration.
.. In fact, my main conclusion after spending ten years of my life working on the TEX project is that software is hard. It’s harder than anything else I’ve ever had to do.
.. If you find that you’re spending almost all your time on theory, start turning some attention to practical things; it will improve your theories. If you find that you’re spending almost all your time on practice, start turning some attention to theoretical things; it will improve your practice.
.. Random numbers should not be generated with a method chosen at random
.. The sun comes up just about as often as it goes down, in the long run, but this doesn’t make its motion random.
.. Science is knowledge which we understand so well that we can teach it to a computer; and if we don’t fully understand something, it is an art to deal with it.
.. In this sense, we should continually be striving to transform every art into a science: in the process, we advance the art.
.. Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.