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defn

core-api



    macro
    boot.janet on line 10, column 1

    (defn name & more)

    Define a function. Equivalent to `(def name (fn name [args] ...))`.

See also:defn-1 exampleSign in to add an example

## Quadratic Formula

(defn qform
  "Use the quadratic formula to solve for x. Returns all real solutions."
  [a b c]
  (def det ( $-$  ( $*$  b b) ( $*$  4 a c)))
  (def factor ( $/$  0.5 a))
  (cond
    (neg? det) []
    (zero? det) [( $*$  factor ( $-$  b))]
    (let [root-det (math/sqrt det)]
        [( $*$  factor ( $-$  ( $-$  b) root-det)) ( $*$  factor ( $+$  ( $-$  b) root-det))])))

    (qform 1 4 3) # -> (-3 -1)

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