Question

From a given double I want to get the next highest number according to some rules which, since I have some difficulty describing them, I will illustrate by examples:

Input      Desired output
-------    --------------
   0.08         0.1
   0.2          0.5
   5           10
   7           10
  99          100
 100          500
2345         5000

The output should be in some sense the ‘next highest multiple of 5 or 10’.

I hope this is understandable; if not, let me know.

The implementation will be in java and input will be positive doubles.

Answer 1

function top5_10 (x) {
  var ten = Math.pow(10, Math.ceiling(Math.ln(x)/Math.LN10)));
  if (ten > 10 * x) { ten = ten / 10; }
  else if (ten <= x) { ten = 10 * ten; }
  return x < ten / 2 ? ten / 2 : ten;
}

or something like this 🙂