diff options
| -rw-r--r-- | modules/math/src/main/clojure/clojure/contrib/math.clj | 40 |
1 files changed, 22 insertions, 18 deletions
diff --git a/modules/math/src/main/clojure/clojure/contrib/math.clj b/modules/math/src/main/clojure/clojure/contrib/math.clj index d4519de9..47629139 100644 --- a/modules/math/src/main/clojure/clojure/contrib/math.clj +++ b/modules/math/src/main/clojure/clojure/contrib/math.clj @@ -3,7 +3,7 @@ ;;; commonly found in Scheme implementations.
;; by Mark Engelberg (mark.engelberg@gmail.com)
-;; January 17, 2009
+;; May 21, 2011
;; expt - (expt x y) is x to the yth power, returns an exact number
;; if the base is an exact number, and the power is an integer,
@@ -92,6 +92,7 @@ exact-integer-sqrt - Implements a math function from the R6RS Scheme (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)
@@ -105,17 +106,17 @@ Returns an exact number if the base is an exact number and the power is an integ (defn- expt-int [base pow]
(loop [n pow, y (num 1), z base]
- (let [t (bit-and n 1), n (bit-shift-right n 1)]
+ (let [t (even? n), n (quot n 2)]
(cond
- (zero? t) (recur n y (* z z))
- (zero? n) (* z y)
- :else (recur n (* z y) (* z z))))))
+ t (recur n y (*' z z))
+ (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)))))
+ :else (/ 1 (expt-int base (-' pow)))))
(defmethod expt :default [base pow] (Math/pow base pow))
@@ -123,7 +124,7 @@ Returns an exact number if the base is an exact number and the power is an integ (cond
(not (number? n)) (throw (IllegalArgumentException.
"abs requires a number"))
- (neg? n) (- n)
+ (neg? n) (-' n)
:else n))
(defmulti ^{:arglists '([n])
@@ -131,10 +132,10 @@ Returns an exact number if the base is an exact number and the power is an integ 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] (.. n (setScale 0 BigDecimal/ROUND_FLOOR) (toBigInteger)))
+(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)))))
+ (dec' (quot (. n numerator) (. n denominator)))))
(defmethod floor :default [n]
(Math/floor n))
@@ -143,9 +144,9 @@ If n is an exact number, floor returns an integer, otherwise a double."} 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] (.. n (setScale 0 BigDecimal/ROUND_CEILING) (toBigInteger)))
+(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)))
+ (if (pos? n) (inc' (quot (. n numerator) (. n denominator)))
(quot (. n numerator) (. n denominator))))
(defmethod ceil :default [n]
(Math/ceil n))
@@ -157,7 +158,8 @@ round always returns an integer. Rounds up for values exactly in between two in (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)))
-(defmethod round :default [n] (Math/round n))
+;; Convert to bigdec in case float/double exceeds range of long
+(defmethod round :default [n] (round (bigdec 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)))
@@ -182,7 +184,9 @@ round always returns an integer. Rounds up for values exactly in between two in (defmethod integer-length java.lang.Long [n]
(count (Long/toBinaryString n)))
(defmethod integer-length java.math.BigInteger [n]
- (count (. n toString 2)))
+ (.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
@@ -191,9 +195,9 @@ round always returns an integer. Rounds up for values exactly in between two in (> n 24)
(let [n-len (integer-length n)]
(loop [init-value (if (even? n-len)
- (bit-shift-left 1 (bit-shift-right n-len 1))
- (bit-shift-left 2 (bit-shift-right n-len 1)))]
- (let [iterated-value (bit-shift-right (+ init-value (quot n init-value)) 1)]
+ (expt 2 (quot n-len 2))
+ (expt 2 (inc (quot n-len 2))))]
+ (let [iterated-value (quot (+' init-value (quot n init-value)) 2)]
(if (>= iterated-value init-value)
init-value
(recur iterated-value)))))
@@ -209,7 +213,7 @@ For example, (exact-integer-sqrt 15) is [3 6] because 15 = 3^2+6." (if (or (not (integer? n)) (neg? n))
(throw (IllegalArgumentException. "exact-integer-sqrt requires a non-negative integer"))
(let [isqrt (integer-sqrt n),
- error (- n (* isqrt isqrt))]
+ error (-' n (*' isqrt isqrt))]
[isqrt error])))
(defmulti ^{:arglists '([n])
@@ -218,7 +222,7 @@ For example, (exact-integer-sqrt 15) is [3 6] because 15 = 3^2+6." (defmethod sqrt ::integer [n]
(if (neg? n) Double/NaN
(let [isqrt (integer-sqrt n),
- error (- n (* isqrt isqrt))]
+ error (-' n (*' isqrt isqrt))]
(if (zero? error) isqrt
(Math/sqrt n)))))
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