clojure.core/with-precision

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Type: macro Added: Clojure 1.0 Examples: 3 Runnable: 0

([precision & exprs])

Sets the precision and rounding mode to be used for BigDecimal operations.

Usage: (with-precision 10 (/ 1M 3)) or: (with-precision 10 :rounding HALF_DOWN (/ 1M 3))

The rounding mode is one of CEILING, FLOOR, HALF_UP, HALF_DOWN, HALF_EVEN, UP, DOWN and UNNECESSARY; it defaults to HALF_UP.

Examples

by Miles on 2010-09-06 . May have evaluation errors. ▶

;; The "M" suffix denotes a BigDecimal instance ;; http://download.oracle.com/javase/6/docs/api/java/math/BigDecimal.html (with-precision 10 (/ 1M 6)) 0.1666666667M (.floatValue 0.1666666667M) 0.16666667

by freckletonj on 2017-03-28 . May have evaluation errors. ▶

;; This may come in handy for example when you use JDBC to grab data ;; from a database, and numbers comes in as BigDecimal. Notice the ;; following ArithmeticException, and solution: (/ 2M 3M) ; => ArithmeticException (with-precision 2 (/ 2M 3M)) ; => 0.67M ;; To make this error more searchable, here's what it is, exactly: ;; ;; Non-terminating decimal expansion; no exact representable decimal result. ;; java.lang.ArithmeticException: Non-terminating decimal expansion; no exact ;; representable decimal result.

by tomdl89 on 2023-10-31 . May have evaluation errors. ▶

(with-precision 1 :rounding UP (* 1.1M 1M)) ;; => 2M (with-precision 1 :rounding CEILING (* 1.1M 1M)) ;; => 2M (with-precision 1 :rounding UP (* -1.1M 1M)) ;; => -2M (with-precision 1 :rounding CEILING (* -1.1M 1M)) ;; => -1M (with-precision 1 :rounding DOWN (* 1.9M 1M)) ;; => 1M (with-precision 1 :rounding FLOOR (* 1.9M 1M)) ;; => 1M (with-precision 1 :rounding DOWN (* -1.9M 1M)) ;; => -1M (with-precision 1 :rounding FLOOR (* -1.9M 1M)) ;; => -2M (with-precision 1 :rounding HALF_EVEN (* 1.5M 1M)) ;; => 2M (with-precision 1 :rounding HALF_EVEN (* 2.5M 1M)) ;; => 2M (with-precision 1 :rounding HALF_EVEN (* -1.5M 1M)) ;; => -2M (with-precision 1 :rounding HALF_EVEN (* -2.5M 1M)) ;; => -2M (with-precision 1 :rounding HALF_UP (* 1.5M 1M)) ;; => 2M (with-precision 1 :rounding HALF_DOWN (* 1.5M 1M)) ;; => 1M (with-precision 1 :rounding HALF_UP (* -1.5M 1M)) ;; => -2M (with-precision 1 :rounding HALF_DOWN (* -1.5M 1M)) ;; => -1M (with-precision 1 :rounding UNNECESSARY (* 1.5M 1M)) ;; => Execution error (ArithmeticException) at… ;; Rounding necessary (with-precision 1 :rounding UNNECESSARY (* 2M 1M)) ;; => 2M

See also

• clojure.core/*math-context*
• clojure.math/round

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