[git] CMU Common Lisp branch master updated. snapshot-2013-11-5-g3a09aa2

[Raymond Toy]

This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "CMU Common Lisp".

The branch, master has been updated
       via  3a09aa24b038be094140ddc86069d0a89eeea5c2 (commit)
      from  f3c9558971d5b0b6aa2b34feb22f44396c90ae33 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit 3a09aa24b038be094140ddc86069d0a89eeea5c2
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Fri Nov 22 20:10:50 2013 -0800

    Darwin doesn't need pi reduction; the C library is accurate enough.
    
    o Make %trig call the C routines directly on Darwin/x86.
    o Add some extra documentation, and a test case.

diff --git a/src/code/irrat.lisp b/src/code/irrat.lisp
index 927a5fb..5944182 100644
--- a/src/code/irrat.lisp
+++ b/src/code/irrat.lisp
@@ -187,14 +187,17 @@
     (%sqrt x))
   )
 
-;;; The standard libm routines for sin, cos, and tan on x86 (Linux)
-;;; and ppc are not very accurate for large arguments when compared to
-;;; sparc (and maxima).  This is basically caused by the fact that
-;;; those libraries do not do an accurate argument reduction.  The
-;;; following functions use some routines Sun's free fdlibm library to
-;;; do accurate reduction.  Then we call the standard C functions (or
-;;; vops for x86) on the reduced argument.  This produces much more
-;;; accurate values.
+;;; The standard libm routines for sin, cos, and tan on x86 (Linux,
+;;; 32-bit.  64-bit is apparently ok) and ppc are not very accurate
+;;; for large arguments when compared to sparc (and maxima).  This is
+;;; basically caused by the fact that those libraries do not do an
+;;; accurate argument reduction.  The following functions use some
+;;; routines Sun's free fdlibm library to do accurate reduction.  Then
+;;; we call the standard C functions (or vops for x86) on the reduced
+;;; argument.  This produces much more accurate values.
+;;;
+;;; You can test this by computing (cos (scale-float 1d0 120)).  The
+;;; true answer is -0.9258790228548379d0.
 
 #+(or ppc x86)
 (progn
@@ -220,7 +223,22 @@
 
 )
 
-#+(or ppc sse2)
+;; If the C library is accurate, use %trig as the Lisp name.
+#-(or ppc (and sse2 (not darwin)))
+(progn
+(declaim (inline %sin %cos %tan))
+(macrolet ((frob (alien-name lisp-name)
+	     `(alien:def-alien-routine (,alien-name ,lisp-name) double-float
+		(x double-float))))
+  (frob "sin" %sin)
+  (frob "cos" %cos)
+  (frob "tan" %tan))
+)
+
+;; Make %%trig be the C library routines that don't do accurate
+;; reduction.  This is for PPC and for any SSE2 build except on
+;; Darwin. Darwin has accurate C library routines.
+#+(or ppc (and sse2 (not darwin)))
 (progn
 (declaim (inline %%sin %%cos %%tan))
 (macrolet ((frob (alien-name lisp-name)
@@ -231,7 +249,10 @@
   (frob "tan" %%tan))
 )
 
-#+(or ppc x86)
+;; When the C library is not accurate, define %trig to do accurate
+;; argument reduction and call the appropriate C function on the
+;; reduced arg.  For x87, we can use the x87 FPU trig instructions.
+#+(or ppc (and x86 (not darwin)))
 (macrolet
     ((frob (sin cos tan)
        `(progn

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

Summary of changes:
 src/code/irrat.lisp |   41 +++++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)


hooks/post-receive
-- 
CMU Common Lisp