A ambg Member Licensed User Longtime User May 22, 2017 #1 I have a variable Double with value x=0.565 round2(x,2) return 0.56 incorrect but if x=1.565 round2(x,2) return 1.57 correct Are there any function for rounding a number like vb.net (math.round) that work correctly? Thanks
I have a variable Double with value x=0.565 round2(x,2) return 0.56 incorrect but if x=1.565 round2(x,2) return 1.57 correct Are there any function for rounding a number like vb.net (math.round) that work correctly? Thanks
Erel B4X founder Staff member Licensed User Longtime User May 22, 2017 #2 0.565 is a decimal value. It cannot be represented precisely in a double value. In this specific value a very small error will cause the rounding to be unstable. You can add a small value to make sure that it rounds up: Code: Copy Round2(x + 0.0000001, 2) With that said, you should avoid using Round2 at all. Use NumberFormat or NumberFormat2 when you want to show the number to the user and keep the more precise value. You can also use the smart string literal: Code: Copy Log($"Value of x is: $1.2{x}"$) Note that the rounding method of NumberFormat is HALF_EVEN: https://docs.oracle.com/javase/7/docs/api/java/math/RoundingMode.html#HALF_EVEN If you want full control over rounding then you should use BigDecimal from the BigNumbers library. Upvote 0
0.565 is a decimal value. It cannot be represented precisely in a double value. In this specific value a very small error will cause the rounding to be unstable. You can add a small value to make sure that it rounds up: Code: Copy Round2(x + 0.0000001, 2) With that said, you should avoid using Round2 at all. Use NumberFormat or NumberFormat2 when you want to show the number to the user and keep the more precise value. You can also use the smart string literal: Code: Copy Log($"Value of x is: $1.2{x}"$) Note that the rounding method of NumberFormat is HALF_EVEN: https://docs.oracle.com/javase/7/docs/api/java/math/RoundingMode.html#HALF_EVEN If you want full control over rounding then you should use BigDecimal from the BigNumbers library.
