- Implemented atanh() and atanhf() which were not listed in the TODO

file but were still unimplemented up until now.

- Replaced ldexp() and modf().


git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@15045 87f5fb63-7c3d-0410-a384-fd976d0f7a62

library/math_atanh.c

@@ -1,5 +1,5 @@
 /*
- * $Id: math_atanh.c,v 1.1 2005-05-29 11:19:00 obarthel Exp $
+ * $Id: math_atanh.c,v 1.2 2005-10-16 09:05:02 obarthel Exp $
  *
  * :ts=4
  *
@@ -29,6 +29,15 @@
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
+ *
+ *
+ * PowerPC math library based in part on work by Sun Microsystems
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
  */
 
 #ifndef _MATH_HEADERS_H
@@ -41,11 +50,31 @@
 
 /****************************************************************************/
 
+static const double zero = 0.0;
+static const double one = 1.0, huge = 1e300;
+
+/****************************************************************************/
+
 double
 atanh(double x)
 {
-	/* ZZZ unimplemented */
-	return(0);
+	double t;
+	LONG hx,ix;
+	ULONG lx;
+	EXTRACT_WORDS(hx,lx,x);
+	ix = hx&0x7fffffff;
+	if ((ix|((lx|(-lx))>>31))>0x3ff00000) /* |x|>1 */
+	    return (x-x)/(x-x);
+	if(ix==0x3ff00000) 
+	    return x/zero;
+	if(ix<0x3e300000&&(huge+x)>zero) return x;	/* x<2**-28 */
+	SET_HIGH_WORD(x,ix);
+	if(ix<0x3fe00000) {		/* x < 0.5 */
+	    t = x+x;
+	    t = 0.5*log1p(t+t*x/(one-x));
+	} else 
+	    t = 0.5*log1p((x+x)/(one-x));
+	if(hx>=0) return t; else return -t;
 }
 
 /****************************************************************************/