Math: Converted multimethods to protocols

1 files changed, 92 insertions, 77 deletions

diff --git a/modules/math/src/main/clojure/clojure/contrib/math.clj b/modules/math/src/main/clojure/clojure/contrib/math.clj
index 807468cf..9faf7072 100644
--- a/modules/math/src/main/clojure/clojure/contrib/math.clj
+++ b/modules/math/src/main/clojure/clojure/contrib/math.clj
@@ -89,21 +89,6 @@ exact-integer-sqrt - Implements a math function from the R6RS Scheme
 "}

   clojure.contrib.math)

 

-(derive ::integer ::exact)

-(derive java.lang.Integer ::integer)

-(derive java.math.BigInteger ::integer)

-(derive clojure.lang.BigInt ::integer)

-(derive java.lang.Long ::integer)

-(derive java.math.BigDecimal ::exact)

-(derive clojure.lang.Ratio ::exact)

-(derive java.lang.Double ::inexact)

-(derive java.lang.Float ::inexact)

-

-(defmulti ^{:arglists '([base pow])

-	     :doc "(expt base pow) is base to the pow power.

-Returns an exact number if the base is an exact number and the power is an integer, otherwise returns a double."}

-  expt (fn [x y] [(class x) (class y)]))

-

 (defn- expt-int [base pow]

   (loop [n pow, y (num 1), z base]

     (let [t (even? n), n (quot n 2)]

@@ -112,14 +97,17 @@ Returns an exact number if the base is an exact number and the power is an integ
        (zero? n) (*' z y)

        :else (recur n (*' z y) (*' z z))))))

 

-(defmethod expt [::exact ::integer] [base pow]

-  (cond

-   (pos? pow) (expt-int base pow)

-   (zero? pow) 1

-   :else (/ 1 (expt-int base (-' pow)))))

-

-(defmethod expt :default [base pow] (Math/pow base pow))

-

+(defn expt

+  "(expt base pow) is base to the pow power.

+Returns an exact number if the base is an exact number and the power is an integer, otherwise returns a double."

+  [base pow]

+  (if (and (not (float? base)) (integer? pow))

+    (cond

+     (pos? pow) (expt-int base pow)

+     (zero? pow) 1

+     :else (/ 1 (expt-int base (-' pow))))

+    (Math/pow base pow)))

+  

 (defn abs "(abs n) is the absolute value of n" [n]

   (cond

    (not (number? n)) (throw (IllegalArgumentException.

@@ -127,39 +115,83 @@ Returns an exact number if the base is an exact number and the power is an integ
    (neg? n) (-' n)

    :else n))

 

-(defmulti ^{:arglists '([n])

-	     :doc "(floor n) returns the greatest integer less than or equal to n.

-If n is an exact number, floor returns an integer, otherwise a double."}

-  floor class)

-(defmethod floor ::integer [n] n)

-(defmethod floor java.math.BigDecimal [n] (bigint (.setScale n 0 BigDecimal/ROUND_FLOOR)))

-(defmethod floor clojure.lang.Ratio [n]

-  (if (pos? n) (quot (. n numerator) (. n denominator))

-      (dec' (quot (. n numerator) (. n denominator)))))

-(defmethod floor :default [n]

-  (Math/floor n))

-

-(defmulti ^{:arglists '([n])

-	     :doc "(ceil n) returns the least integer greater than or equal to n.

-If n is an exact number, ceil returns an integer, otherwise a double."}

-  ceil class)

-(defmethod ceil ::integer [n] n)

-(defmethod ceil java.math.BigDecimal [n] (bigint (.setScale n 0 BigDecimal/ROUND_CEILING)))

-(defmethod ceil clojure.lang.Ratio [n]

-  (if (pos? n) (inc' (quot (. n numerator) (. n denominator)))

-      (quot (. n numerator) (. n denominator))))

-(defmethod ceil :default [n]

-  (Math/ceil n))

-

-(defmulti ^{:arglists '([n])

-	     :doc "(round n) rounds to the nearest integer.

-round always returns an integer.  Rounds up for values exactly in between two integers."}

-  round class)

-(defmethod round ::integer [n] n)

-(defmethod round java.math.BigDecimal [n] (floor (+ n 0.5M)))

-(defmethod round clojure.lang.Ratio [n] (floor (+ n 1/2)))

-;; Convert to bigdec in case float/double exceeds range of long

-(defmethod round :default [n] (round (bigdec n)))

+(defprotocol MathFunctions

+  (floor [n] "(floor n) returns the greatest integer less than or equal to n.

+If n is an exact number, floor returns an integer, otherwise a double.")

+  (ceil [n] "(ceil n) returns the least integer greater than or equal to n.

+If n is an exact number, ceil returns an integer, otherwise a double.")

+  (round [n] "(round n) rounds to the nearest integer.

+round always returns an integer.  Rounds up for values exactly in between two integers.")

+  (integer-length [n] "Length of integer in binary")

+  (sqrt [n] "Square root, but returns exact number if possible."))

+

+(declare sqrt-integer)

+(declare sqrt-ratio)

+(declare sqrt-decimal)

+

+(extend-type

+ Integer MathFunctions

+ (floor [n] n)

+ (ceil [n] n)

+ (round [n] n)

+ (integer-length [n] (- 32 (Integer/numberOfLeadingZeros n)))

+ (sqrt [n] (sqrt-integer n)))

+

+(extend-type

+ Long MathFunctions

+ (floor [n] n)

+ (ceil [n] n)

+ (round [n] n)

+ (integer-length [n] (- 64 (Long/numberOfLeadingZeros n)))

+ (sqrt [n] (sqrt-integer n)))

+

+(extend-type

+ java.math.BigInteger MathFunctions

+ (floor [n] n)

+ (ceil [n] n)

+ (round [n] n)

+ (integer-length [n] (.bitLength n))

+ (sqrt [n] (sqrt-integer n)))

+

+(extend-type

+ clojure.lang.BigInt MathFunctions

+ (floor [n] n)

+ (ceil [n] n)

+ (round [n] n)

+ (integer-length [n] (.bitLength n))

+ (sqrt [n] (sqrt-integer n)))

+

+(extend-type

+ java.math.BigDecimal MathFunctions

+ (floor [n] (bigint (.setScale n 0 BigDecimal/ROUND_FLOOR)))

+ (ceil [n] (bigint (.setScale n 0 BigDecimal/ROUND_CEILING)))

+ (round [n] (floor (+ n 0.5M)))

+ (sqrt [n] (sqrt-decimal n)))

+

+(extend-type

+ clojure.lang.Ratio MathFunctions

+ (floor [n]

+	(if (pos? n) (quot (. n numerator) (. n denominator))

+	    (dec' (quot (. n numerator) (. n denominator)))))

+ (ceil [n]

+       (if (pos? n) (inc' (quot (. n numerator) (. n denominator)))

+	   (quot (. n numerator) (. n denominator))))

+ (round [n] (floor (+ n 1/2)))

+ (sqrt [n] (sqrt-ratio n)))

+

+(extend-type

+ Double MathFunctions

+ (floor [n] (Math/floor n))

+ (ceil [n] (Math/ceil n))

+ (round [n] (round (bigdec n)))

+ (sqrt [n] (Math/sqrt n)))

+

+(extend-type

+ Float MathFunctions

+ (floor [n] (Math/floor n))

+ (ceil [n] (Math/ceil n))

+ (round [n] (round (bigdec n)))

+ (sqrt [n] (Math/sqrt n)))

 

 (defn gcd "(gcd a b) returns the greatest common divisor of a and b" [a b]

   (if (or (not (integer? a)) (not (integer? b)))

@@ -177,17 +209,6 @@ round always returns an integer.  Rounds up for values exactly in between two in
         (zero? b) 0

         :else (abs (*' b (quot a (gcd a b))))))

 

-; Length of integer in binary, used as helper function for sqrt.

-(defmulti ^{:private true} integer-length class)

-(defmethod integer-length java.lang.Integer [n]

-  (count (Integer/toBinaryString n)))

-(defmethod integer-length java.lang.Long [n]

-  (count (Long/toBinaryString n)))

-(defmethod integer-length java.math.BigInteger [n]

-  (.bitLength n))

-(defmethod integer-length clojure.lang.BigInt [n]

-  (.bitLength n))

-

 ;; Produces the largest integer less than or equal to the square root of n

 ;; Input n must be a non-negative integer

 (defn- integer-sqrt [n]

@@ -216,17 +237,14 @@ For example, (exact-integer-sqrt 15) is [3 6] because 15 = 3^2+6."
 	  error (-' n (*' isqrt isqrt))]

       [isqrt error])))

 

-(defmulti ^{:arglists '([n])

-	     :doc "Square root, but returns exact number if possible."}

-  sqrt class)

-(defmethod sqrt ::integer [n]

+(defn- sqrt-integer [n]

   (if (neg? n) Double/NaN

       (let [isqrt (integer-sqrt n),

 	    error (-' n (*' isqrt isqrt))]

 	(if (zero? error) isqrt

 	    (Math/sqrt n)))))

 

-(defmethod sqrt clojure.lang.Ratio [n]

+(defn- sqrt-ratio [n]

   (if (neg? n) Double/NaN

       (let [numerator (.numerator n),

 	    denominator (.denominator n),

@@ -238,14 +256,11 @@ For example, (exact-integer-sqrt 15) is [3 6] because 15 = 3^2+6."
 	      (Math/sqrt n)

 	      (/ sqrtnum sqrtden)))))))

 

-(defmethod sqrt java.math.BigDecimal [n]

+(defn- sqrt-decimal [n]

   (if (neg? n) Double/NaN

       (let [frac (rationalize n),

 	    sqrtfrac (sqrt frac)]

 	(if (ratio? sqrtfrac)

 	  (/ (BigDecimal. (.numerator sqrtfrac))

 	     (BigDecimal. (.denominator sqrtfrac)))

-	  sqrtfrac))))

-

-(defmethod sqrt :default [n]

-  (Math/sqrt n))

+	  sqrtfrac))))
\ No newline at end of file