--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/kernel/eka/euser/maths/um_tan.cpp	Mon Oct 19 15:55:17 2009 +0100
@@ -0,0 +1,132 @@
+// Copyright (c) 1995-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// e32\euser\maths\um_tan.cpp
+// Tangent.
+// 
+//
+
+#include "um_std.h"
+
+#if defined(__USE_VFP_MATH) && !defined(__CPU_HAS_VFP)
+#error	__USE_VFP_MATH was defined but not __CPU_HAS_VFP - impossible combination, check variant.mmh 
+#endif
+
+
+#ifndef __USE_VFP_MATH
+
+LOCAL_D const TUint32 TanCoeffs[] =
+	{
+	0x2168C235,0xC90FDAA2,0x7FFF0000,	// polynomial approximation to tan((pi/2)*x)
+	0x2DF4707D,0xA55DE731,0x7FFF0000,	// for |x|<=0.25
+	0xA9A1A71A,0xA335E33B,0x7FFF0000,
+	0x0BB9E431,0xA2FFFCDD,0x7FFF0000,
+	0x3E523A39,0xA2FA3863,0x7FFF0000,
+	0x8A35C401,0xA2F9D38B,0x7FFF0000,
+	0x91269411,0xA2F16003,0x7FFF0000,
+	0xDA32CC78,0xA3A93B13,0x7FFF0000,
+	0x4FB88317,0x9A146197,0x7FFF0000,
+	0x0D787ECE,0xE131DEE5,0x7FFF0000
+	};
+
+LOCAL_D const TUint32 Onedata[] = {0x00000000,0x80000000,0x7FFF0000};		// 1.0
+LOCAL_D const TUint32 Halfdata[] = {0x00000000,0x80000000,0x7FFE0000};		// 0.5
+LOCAL_D const TUint32 PiBy2Invdata[] = {0x4E44152A,0xA2F9836E,0x7FFE0000};	// 2/pi
+
+
+
+
+EXPORT_C TInt Math::Tan(TReal& aTrg, const TReal& aSrc)
+/**
+Calculates the tangent of a number.
+
+@param aTrg A reference containing the result.
+@param aSrc The argument of the tan function in radians. 
+
+@return KErrNone if successful, otherwise another of
+        the system-wide error codes. 
+*/
+	{
+	// Calculate tan(aSrc) and write result to aTrg.
+	// Algorithm:
+	//		Let x=aSrc/(pi/2). Throw away integer part, but if integer part odd
+	//			then replace final result y with -1/y
+	//			( use identities tan(x+n*pi)=tan(x), tan(x+pi/2)=-1/tan(x) )
+	//		Replace x with fractional part after division.
+	//		If x>=0.5, replace x with 1-x and replace result y with 1/y
+	//			( use identity tan(pi/2-x)=1/tan(x) )
+	//		If x>=0.25, replace x with 0.5-x and replace result y with (1-y)/(1+y)
+	//			( use identity tan(pi/4-x)=(1-tan(x))/(1+tan(x)) )
+	//		Use polynomial approximation to calculate tan(pi*x/2) for |x|<=0.25
+
+	const TRealX& One = *(const TRealX*)Onedata;
+	const TRealX& Half = *(const TRealX*)Halfdata;
+	const TRealX& PiBy2Inv = *(const TRealX*)PiBy2Invdata;
+
+	TRealX x;
+	TInt r=x.Set(aSrc);
+	if (r==KErrNone)
+		{
+		TInt8 sign=x.iSign;
+		x.iSign=0;
+		x*=PiBy2Inv;
+		TInt n=(TInt)x;
+		if (n<KMaxTInt && n>KMinTInt)
+			{
+			TInt flags=(n&1)<<1;
+			x-=TRealX(n);
+			if (x.iExp>=0x7FFE)
+				{
+				x=One-x;
+				flags^=2;
+				}
+			if (x.iExp>=0x7FFD)
+				{
+				x=Half-x;
+				flags^=1;
+				}
+			TRealX y;
+			PolyX(y,x*x,9,(const TRealX*)TanCoeffs);
+			y*=x;
+			if (flags==3)
+				y=(One+y)/(One-y);
+			else if (flags==2)
+				y=One/y;
+			else if (flags==1)
+				y=(One-y)/(One+y);
+			y.iSign=TInt8(sign ^ (n&1));
+			return y.GetTReal(aTrg);
+			}
+		}
+	SetNaN(aTrg);
+	return KErrArgument;
+	}
+
+#else // __USE_VFP_MATH
+
+// definitions come from RVCT math library
+extern "C" TReal tan(TReal);
+
+EXPORT_C TInt Math::Tan(TReal& aTrg, const TReal& aSrc)
+	{
+	if (aSrc<KMaxTInt && aSrc>KMinTInt)
+		{
+		aTrg = tan(aSrc);
+		if (Math::IsFinite(aTrg))
+			return KErrNone;
+		}
+	SetNaN(aTrg);
+	return KErrArgument;
+	}
+
+#endif