Yet further adjust degree-based trig functions for more portability.

tglsfdc · tglsfdc · commit 00347575e275 · 2016-01-24T12:53:03.000-05:00
Buildfarm member cockatiel is still saying that cosd(60) isn't 0.5.
What seems likely is that the subexpression (1.0 - cos(x)) isn't being
rounded to double width before more arithmetic is done on it, so force
that by storing it into a variable.
diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
@@ -2000,7 +2000,9 @@ sind_0_to_30(double x)
 static double
 cosd_0_to_60(double x)
 {
-	return 1.0 - ((1.0 - cos(x * RADIANS_PER_DEGREE)) / one_minus_cos_60) / 2.0;
+	float8		one_minus_cos_x = 1.0 - cos(x * RADIANS_PER_DEGREE);
+
+	return 1.0 - (one_minus_cos_x / one_minus_cos_60) / 2.0;
 }
 
 

Original file line number	Diff line number	Diff line change
`@@ -2000,7 +2000,9 @@ sind_0_to_30(double x)`
`2000`	`2000`	`static double`
`2001`	`2001`	`cosd_0_to_60(double x)`
`2002`	`2002`	`{`
`2003`		`- return 1.0 - ((1.0 - cos(x * RADIANS_PER_DEGREE)) / one_minus_cos_60) / 2.0;`
	`2003`	`+ float8 one_minus_cos_x = 1.0 - cos(x * RADIANS_PER_DEGREE);`
	`2004`	`+`
	`2005`	`+ return 1.0 - (one_minus_cos_x / one_minus_cos_60) / 2.0;`
`2004`	`2006`	`}`
`2005`	`2007`
`2006`	`2008`