All of the other answers have missed how hard it is to do this properly. You can do a first cut approach at this which is accurate to a certain extent, but until you take into account IEEE rounding modes (et al), you will never have the right answer. I’ve written naive implementations before with … Read more
BigDecimal is immutable, any operation on it including setScale(2, BigDecimal.ROUND_HALF_UP) produces a new BigDecimal. Correct code should be BigDecimal bd = new BigDecimal(1); bd.setScale(2, BigDecimal.ROUND_HALF_UP); // this does change bd bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP); System.out.println(bd); output 1.00 Note – Since Java 9 BigDecimal.ROUND_HALF_UP has been deprecated and you should now use RoundingMode.ROUND_HALF_UP.
23 fraction bits (22-0) of the significand appear in the memory format but the total precision is actually 24 bits since we assume there is a leading 1. This is equivalent to log10(2^24) ≈ 7.225 decimal digits. Double-precision float has 52 bits in fraction, plus the leading 1 is 53. Therefore a double can hold … Read more
Floating point numbers (in this case doubles) cannot represent decimal values exactly. I would recommend reading David Goldberg’s What every computer scientist should know about floating-point arithmetic This applies to all languages that deal with floating point numbers whether it be C#, Java, JavaScript, … This is essential reading for any developer working with floating … Read more
Have been there 🙂 I also travelled through Stackoverflow’s PiP-suggestions, including your reference and this thread. Unfortunately, none of the suggestions (at least those I tried) were flawless and sufficient for a real-life scenario: like users plotting complex polygons on a Google map in freehand, “vicious” right vs left issues, negative numbers and so on. … Read more
Trying to do this is a mistake. Throwing more precision at a problem is a tempting trap for newcomers to floating-point, but it’s not that useful, especially to this extreme. Your operations wouldn’t actually require the “largest possible” precision even if that was a well-defined notion. Either they require exact arithmetic, in which case decimal.Decimal … Read more
Historical note: the comment thread below may refer to first and second implementations. I swapped the order in September 2017 since leading with a buggy implementation caused confusion. If you want something that maps “0.1e-100” to 101, then you can try something like function decimalPlaces(n) { // Make sure it is a number and use … Read more
The f suffix makes it a single precision(float) literal instead of a double precision literal. This usually means 32 bit instead of 64 bit floats. Floating-point constants default to type double. By using the suffixes f or l (or F or L — the suffix is not case sensitive), the constant can be specified as … Read more
It can be useful to represent a number including its accuracy – so 0.5m could be used to mean “anything between 0.45m and 0.55m” (with appropriate limits) and 0.50m could be used to mean “anything between 0.495m and 0.545m”. I suspect that most developers don’t actually use this functionality, but I can see how it … Read more