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Float.round

rounddecimal_placesrounding_mode

Group: Rounding

Documentation​

Round to a specified number of decimal places. By default, rounding uses "symmetric round-half-up", also known as "half-up." If rounding_mode=Rounding_Mode.Bankers, then it uses "round-half-even", also known as "banker's rounding". If decimal_places > 0, round returns a Float; otherwise, it returns an Integer. If the argument is NaN or +/-Inf, an Arithmetic_Error error is thrown.

Arguments​

  • decimal_places: The number of decimal places to round to. Can be negative, which results in rounding to positive integer powers of 10. Must be between -15 and 15 (inclusive).
  • rounding_mode: specifies how to break ties for the least significant digit.

Examples​

Round to the nearest integer.​

     3.3 . round == 3

Round to two decimal places.​

     3.1415 . round 2 == 3.14

Round to the nearest hundred.​

     1234.0 . round -2 == 1200

Use Banker's Rounding.​

     2.5 . round rounding_mode=Rounding_Mode.Bankers == 2

Errors​

If self is outside the range -99999999999999..99999999999999 (inclusive), an Illegal_Argument error is thrown. If decimal_places is outside the range -15..15 (inclusive), an Illegal_Argument error is thrown.

Remarks​

Negative decimal place counts​

Rounding to n digits can be thought of as "rounding to the nearest multiple of 10^(-n)". For negative decimal counts, this results in rounding to the nearest positive integer power of 10.