[Cmucl-cvs] [git] CMU Common Lisp branch master updated. snapshot-2014-11-23-g37d383a
Raymond Toy
rtoy at common-lisp.net
Wed Nov 26 22:04:38 UTC 2014
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- Log -----------------------------------------------------------------
commit 37d383ae57c2fc9597cb87eac9551af866885cd3
Author: Raymond Toy <toy.raymond at gmail.com>
Date: Wed Nov 26 14:04:29 2014 -0800
Fix some issues with log2 and log10 of big rationals.
* src/code/irrat.lisp:
* Add log10 function to handle the computation of the base 10 log
of big rationals that might not fit in a double-float.
* Fix some issues where CL:LOG wasn't handling logs of big
rationals. (A regression).
* tests/trac.lisp:
* Update trac.8 test to include logs base 10.
diff --git a/src/code/irrat.lisp b/src/code/irrat.lisp
index 568fa46..325e5bc 100644
--- a/src/code/irrat.lisp
+++ b/src/code/irrat.lisp
@@ -645,6 +645,19 @@
(log2-bignum x)
(+ n frac))))))
+;; Handle the case where number could be so large that it doesn't fit
+;; in a double-float.
+(defun log10 (number &optional (float-type 1d0))
+ (let ((d (ignore-errors (float number 1d0))))
+ (cond (d
+ ;; Number fits in a double, so it's easy
+ (float (%log10 d) float-type))
+ (t
+ ;; Number doesn't fit in a double. Do it the hard way.
+ ;; This should be done more accurately.
+ (/ (log2 number float-type)
+ (log2 (float 10 float-type)))))))
+
(defun log (number &optional (base nil base-p))
"Return the logarithm of NUMBER in the base BASE, which defaults to e."
(if base-p
@@ -667,12 +680,17 @@
((double-float
(foreach integer ratio single-float double-float))
(%log2 number))
- (((foreach integer ratio single-float)
+ ((single-float double-float)
+ (%log2 (float number 1d0)))
+ ((single-float
(foreach integer ratio single-float))
(float (%log2 (float number 1d0)) 1f0))
- (((foreach integer ratio single-float)
+ (((foreach integer ratio)
+ (foreach integer ratio single-float))
+ (log2 number 1f0))
+ (((foreach integer ratio)
double-float)
- (%log2 (float number 1d0)))
+ (log2 number 1d0))
#+double-double
(((foreach integer ratio single-float double-float)
double-double-float)
@@ -690,14 +708,19 @@
;; log base 2 and 10 for non-negative arguments.
(number-dispatch ((number real) (base real))
((double-float
- (foreach rational single-float double-float))
+ (foreach integer ratio single-float double-float))
(%log10 number))
- (((foreach integer ratio single-float)
+ ((single-float double-float)
+ (%log10 (float number 1d0)))
+ ((single-float
(foreach integer ratio single-float))
(float (%log10 (float number 1d0)) 1f0))
- (((foreach integer ratio single-float)
+ (((foreach integer ratio)
+ (foreach integer ratio single-float))
+ (log10 number 1f0))
+ (((foreach integer ratio)
double-float)
- (%log10 (float number 1d0)))
+ (log10 number 1d0))
#+double-double
(((foreach integer ratio single-float double-float)
ext:double-double-float)
diff --git a/tests/trac.lisp b/tests/trac.lisp
index 2bf420d..198a24d 100644
--- a/tests/trac.lisp
+++ b/tests/trac.lisp
@@ -22,7 +22,7 @@
(:tag :trac)
(assert-false
(let (failures)
- (dolist (base (list nil 2 2.0 2d0
+ (dolist (base (list nil 2 2.0 2d0 10 10.0 10d0
(ash 1 99) (ash 1 3000)
8/7 (/ (ash 1 3000) 7)))
(dolist (number (list 100 100.0 100d0
-----------------------------------------------------------------------
Summary of changes:
src/code/irrat.lisp | 37 ++++++++++++++++++++++++++++++-------
tests/trac.lisp | 2 +-
2 files changed, 31 insertions(+), 8 deletions(-)
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