Calculation vs DataStructure vs Logic

We've stated before that the best solution to a problem is the simplest adequate one; for any problem we should strive for the simplest approach. Suppose we must write code to fulfill the following specification:

if the input argument is 1, the output is 10
if the input argument is 2, the output is 12
if the input argument is 3, the output is 14

There are three aproaches we could take:

1.Calculation:

out = 10 + ((in - 1) * 2)

2. Data Structure

int anarray [] {10,12,14};
out = anarray[in -1];

3. Logic

switch(in) {
    case 0: out = 10; break;
    case 1: out = 12; break;
    case 2: out = 14; break;

}

In this problem, calculation is simplest. Assuming it is also adequate (speed is not critical), calculation is best.

The problem of converting angles to sines and cosines can be implemented more simply (at least in terms of lines of code and object size) by calcualting the answer than by using a data structure. But for many application requiring trig, it's faster to look up the answer in a table stored in memory. In this case, the simplest adequate solution is using the data structure.

In choosing which approach to apply towards solving a problem, give preference in the following order:

1. Calculation (except when speed counts)
2. Data structure
3. Logic