When programming, think like a computer

When programming, it is best to think like a computer. It is tempting to think like a human. But humans think very differently than computers (if we allow that computers think), and thinking like a human leads to complex programs.

This was brought home to me while reading William Conley's "Computer Optimization Techniques" which discusses the solutions to Integer Programming problems and related problems. Many of these problems can be solved with brute-force calculations, evaluating every possible solution and identifying the most profitable (or least expensive).

The programs for these brute-force methods are short and simple. Even in FORTRAN, they run less than fifty lines. Their brevity is due to their simplicity. There is no clever coding, no attempt to optimize the algorithm. The programs take advantage of the computer's strength of fast computation.

Humans think very differently. They tire quickly of routine calculations. They can identify patterns and have insights into shortcuts for algorithms. They can take creative leaps to solutions. These are all survival skills, useful for dealing with an uncertain environment and capable predators. But they are quite difficult to encode into a computer program. So hard that it is often more efficient to use brute-force calculations without insights and creative leaps. The time spent making the program "smart" is larger than the time saved by the improved program.

Brute-force is not always the best method for calculations. Sometimes you need a smart program, because the number of computations is staggering. In those cases, it is better to invest the time in improvements. (To his credit, Conley shows techniques to reduce the computations, sometimes by increasing the complexity of the code.)

Computing efficiency (that is, "smart" programs) has been a concern since the first computing machines were made. Necessary at first, the need for efficiency drops over time. Mainframe computers became faster, which allowed for "sloppy" programs ("sloppy" meaning "anything less than maximum efficiency").

Minicomputers were slower than mainframes, significantly less expensive, and another step away from the need for optimized, "smart" programs. PCs were another step. Today, smart phones have more computing power than PCs of a few years ago, at a fraction of the price. Cloud computing, a separate branch in the evolution of computing, offers cheap, readily-available computing power.

I won't claim that computing power is (or will ever be) "too cheap to meter". But it is cheap, and it is plentiful. And with cheap and plentiful computing power, we can build programs that use simple methods.

When writing a computer program, think like a computer. Start with a simple algorithm, one that is not clever. Chances are, it will be good enough.