[cmucl-commit] [git] CMU Common Lisp branch master updated. snapshot-2014-11-30-g5f81e24

[Raymond Toy]

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- Log -----------------------------------------------------------------
commit 5f81e24180fa7721fcad38b9ae3419bd9f2a221d
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Sun Nov 30 18:24:59 2014 -0800

    Fix to handle (log 3/2 2) and (log -3/2 2).  Test added.
    
     * src/code/irrat.lisp:
       * Fix LOG2 to handle the case of negative rational numbers.
       * Fix LOG of rational to a rational base. We want to convert the
         log of the number to a single float because log2 isn't intended
         to handle single-float type.
    
     * tests/irrat.lisp:
       * Add test for log of rational to rational base.
       * Add some additional tests for dd-%log2.

diff --git a/src/code/irrat.lisp b/src/code/irrat.lisp
index 0804ef9..b21b92f 100644
--- a/src/code/irrat.lisp
+++ b/src/code/irrat.lisp
@@ -632,8 +632,11 @@
 	 ;; it, and converting it to double-float is accurate.
 	 (if (= (integer-length top)
 		(integer-length bot))
-	     (/ (log1p (float (- x 1) float-type))
-		(log-of-2 float-type))
+	     (let ((log-abs (/ (log1p (float (- (abs x) 1) float-type))
+			       (log-of-2 float-type))))
+	       (if (minusp x)
+		   (complex log-abs (log-2-pi float-type))
+		   log-abs))
 	     (multiple-value-bind (top-n top-frac)
 		 (log2-bignum top)
 	       (multiple-value-bind (bot-n bot-frac)
@@ -687,10 +690,10 @@
 		   (float (%log2 (float number 1d0)) 1f0))
 		  (((foreach integer ratio)
 		    (foreach integer ratio single-float))
-		   (log2 number 1f0))
+		   (float (log2 number) 1f0))
 		  (((foreach integer ratio)
 		    double-float)
-		   (log2 number 1d0))
+		   (log2 number))
 		  #+double-double
 		  (((foreach single-float double-float)
 		    double-double-float)
diff --git a/tests/irrat.lisp b/tests/irrat.lisp
index a6a405d..14db13e 100644
--- a/tests/irrat.lisp
+++ b/tests/irrat.lisp
@@ -37,6 +37,22 @@
 	(assert-true (typep result true-type)
 		     result true-type)))))
 
+(define-test log2.special-cases
+  (let* ((y (log 3/2 2))
+	 (e (relerr y 0.5849625007211562d0)))
+    (assert-true (<= e
+		     2.308d-8)
+		 e y))
+  (let* ((y (log -3/2 2))
+	 (ry (realpart y))
+	 (iy (imagpart y))
+	 (er (relerr ry 0.5849625007211562d0))
+	 (ei (relerr iy (/ pi (log 2d0)))))
+    (assert-true (<= er 2.308d-8)
+		 er ry)
+    (assert-true (<= ei 1.433d-8)
+		 ei iy)))
+
 ;; This tests that log base 10 returns the correct value and the
 ;; correct type.
 (define-test log10.result-types
@@ -129,3 +145,10 @@
 	  do (assert-true (<= e threshold)
 			  k e x y))))
 
+
+(define-test log2.relationships
+  (loop for k from 1 below 1000
+	for x = (expt 1.1w0 k)
+	for logx = (kernel::dd-%log2 x)
+	for log1/x = (kernel::dd-%log2 (/ x))
+	do (assert-true (<= (abs (+ logx log1/x)) (* 1 double-float-epsilon)))))

-----------------------------------------------------------------------

Summary of changes:
 src/code/irrat.lisp | 11 +++++++----
 tests/irrat.lisp    | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)


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