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Handle -0.0 correctly in tan() and cot().

--- a/lib/math/tan-impl.myr

+++ b/lib/math/tan-impl.myr

@@ -358,12 +358,25 @@

 }

 const tanorcot = {x : flt64, want_tan : bool

-	var e : int64

-	(_, e, _) = std.flt64explode(x)

+	var n : bool, e : int64, s : uint64

+	(n, e, s) = std.flt64explode(x)

+

 	if e == 1024

 		-> (std.flt64nan(), 0.0)

 	;;

+	if e == -1023 && s == 0x0

+		/* Special handling for +/-0.0 */

+		match (n, want_tan)

+		| (false, false): -> (std.flt64frombits(0x7ff0000000000000), 0.0)

+		| (false, true ): -> (std.flt64frombits(0x0000000000000000), 0.0)

+		| (true , false): -> (std.flt64frombits(0xfff0000000000000), 0.0)

+		| (true , true ): -> (std.flt64frombits(0x8000000000000000), 0.0)

+		;;

+	;;

+

+

+

 	var N : int64

 	var x1 : flt64, x2 : flt64

@@ -410,7 +423,7 @@

 	var p1, p2

 	/*

-	  Since cot() can blow up close to 0, just fall back to polynomial approximation

+	   Since cot() can blow up close to 0, just fall back to polynomial approximation

 	 */

 	if x1 < 0.060546875

 		var s = x1 * x1

--- a/lib/math/test/tan-impl.myr

+++ b/lib/math/test/tan-impl.myr

@@ -40,7 +40,9 @@

 const tancot01 = {c

 	var inputs : (uint32, uint32, uint32)[:] = [

 		(0x00000000, 0x00000000, 0x7f800000),

+		(0x80000000, 0x80000000, 0xff800000),

 		(0x01000000, 0x01000000, 0x7e000000),

+		(0x3c000000, 0x3c0000ab, 0x42fffeab),

 	][:]

 	for (x, yt, yc) : inputs

@@ -65,6 +67,7 @@

 const tancot02 = {c

 	var inputs : (uint64, uint64, uint64)[:] = [

 		(0x0000000000000000, 0x0000000000000000, 0x7ff0000000000000),

+		(0x8000000000000000, 0x8000000000000000, 0xfff0000000000000),

 		(0x5101000000000000, 0xbff4f77bbc53c8f9, 0xbfe86b6d64c43ec0),

 		(0x4b01000000000000, 0xbfe96f60bbc6c837, 0xbff421332f057cb5),

 		(0x41bb951f1572eba5, 0xbc8f54f5227a4e84, 0xc35057584c429b3a), /* [GB91]'s "Xhard" */

@@ -94,6 +97,7 @@

 const tancot03 = {c

 	var inputs : (uint64, uint64, uint64, uint64, uint64)[:] = [

 		(0xf83b13a6a142b6d5, 0xbf5a86f73542c78a, 0xc0834d0a344cbe85, 0xbf5a86f73542c789, 0xc0834d0a344cbe85),

+		(0x3f80000000000000, 0x3f800015557777af, 0x405fffd55549f49b, 0x3f800015557777af, 0x405fffd55549f49a),

 	][:]

 	for (x, yt_perfect, yc_perfect, yt_acceptable, yc_acceptable) : inputs