redo and clean up math.

R=r
DELTA=243  (60 added, 72 deleted, 111 changed)
OCL=22909
CL=22912

1 files changed, 22 insertions, 25 deletions

diff --git a/src/lib/math/atan.go b/src/lib/math/atan.go
index f2fd7ed33..730d50a51 100644
--- a/src/lib/math/atan.go
+++ b/src/lib/math/atan.go
@@ -4,6 +4,8 @@
 
 package math
 
+import "math"
+
 /*
  *	floating-point arctangent
  *
@@ -13,32 +15,27 @@ package math
  *	coefficients are #5077 from Hart & Cheney. (19.56D)
  */
 
-const
-(
-	ap4	= .161536412982230228262e2;
-	ap3	= .26842548195503973794141e3;
-	ap2	= .11530293515404850115428136e4;
-	ap1	= .178040631643319697105464587e4;
-	ap0	= .89678597403663861959987488e3;
-	aq4	= .5895697050844462222791e2;
-	aq3	= .536265374031215315104235e3;
-	aq2	= .16667838148816337184521798e4;
-	aq1	= .207933497444540981287275926e4;
-	aq0	= .89678597403663861962481162e3;
-	apio2	= .15707963267948966192313216e1;
-	apio4	= .7853981633974483096156608e0;
-	asq2p1	= .2414213562373095048802e1;		// sqrt(2)+1
-	asq2m1	= .414213562373095048802e0;		// sqrt(2)-1
-)
-
 /*
  *	xatan evaluates a series valid in the
  *	range [-0.414...,+0.414...]. (tan(pi/8))
  */
 func xatan(arg float64) float64 {
-	argsq := arg*arg;
-	value := ((((ap4*argsq + ap3)*argsq + ap2)*argsq + ap1)*argsq + ap0);
-	value = value/(((((argsq + aq4)*argsq + aq3)*argsq + aq2)*argsq + aq1)*argsq + aq0);
+	const
+	(
+		P4	= .161536412982230228262e2;
+		P3	= .26842548195503973794141e3;
+		P2	= .11530293515404850115428136e4;
+		P1	= .178040631643319697105464587e4;
+		P0	= .89678597403663861959987488e3;
+		Q4	= .5895697050844462222791e2;
+		Q3	= .536265374031215315104235e3;
+		Q2	= .16667838148816337184521798e4;
+		Q1	= .207933497444540981287275926e4;
+		Q0	= .89678597403663861962481162e3;
+	)
+	sq := arg*arg;
+	value := ((((P4*sq + P3)*sq + P2)*sq + P1)*sq + P0);
+	value = value/(((((sq + Q4)*sq + Q3)*sq + Q2)*sq + Q1)*sq + Q0);
 	return value*arg;
 }
 
@@ -47,13 +44,13 @@ func xatan(arg float64) float64 {
  *	to the range [0,0.414...] and calls xatan.
  */
 func satan(arg float64) float64 {
-	if arg < asq2m1 {
+	if arg < Sqrt2 - 1 {
 		return xatan(arg);
 	}
-	if arg > asq2p1 {
-		return apio2 - xatan(1/arg);
+	if arg > Sqrt2 + 1 {
+		return Pi/2 - xatan(1/arg);
 	}
-	return apio4 + xatan((arg-1)/(arg+1));
+	return Pi/4 + xatan((arg-1)/(arg+1));
 }
 
 /*