10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29 
  30 #pragma weak acosh = __acosh
  31 
  32 /* INDENT OFF */
  33 /*
  34  * acosh(x)
  35  * Method :
  36  *      Based on
  37  *              acosh(x) = log [ x + sqrt(x*x-1) ]
  38  *      we have
  39  *              acosh(x) := log(x)+ln2, if x is large; else
  40  *              acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x > 2; else
  41  *              acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t = x-1.
  42  *
  43  * Special cases:
  44  *      acosh(x) is NaN with signal if x < 1.
  45  *      acosh(NaN) is NaN without signal.
  46  */
  47 /* INDENT ON */
  48 
  49 #include "libm_synonyms.h"      /* __acosh, __log, __log1p */
  50 #include "libm_protos.h"        /* _SVID_libm_error */
  51 #include "libm_macros.h"
  52 #include <math.h>
  53 
  54 static const double
  55         one = 1.0,
  56         ln2 = 6.93147180559945286227e-01;       /* 3FE62E42, FEFA39EF */
  57 
  58 double
  59 acosh(double x) {
  60         double t;
  61         int hx;
  62 
  63         hx = ((int *) &x)[HIWORD];
  64         if (hx < 0x3ff00000) {       /* x < 1 */
  65                 if (isnan(x))
  66 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
  67                         return (hx >= 0xfff80000 ? x : (x - x) / (x - x));
  68                         /* assumes sparc-like QNaN */
  69 #else

  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29 
  30 #pragma weak __acosh = acosh
  31 
  32 /* INDENT OFF */
  33 /*
  34  * acosh(x)
  35  * Method :
  36  *      Based on
  37  *              acosh(x) = log [ x + sqrt(x*x-1) ]
  38  *      we have
  39  *              acosh(x) := log(x)+ln2, if x is large; else
  40  *              acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x > 2; else
  41  *              acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t = x-1.
  42  *
  43  * Special cases:
  44  *      acosh(x) is NaN with signal if x < 1.
  45  *      acosh(NaN) is NaN without signal.
  46  */
  47 /* INDENT ON */
  48 

  49 #include "libm_protos.h"        /* _SVID_libm_error */
  50 #include "libm_macros.h"
  51 #include <math.h>
  52 
  53 static const double
  54         one = 1.0,
  55         ln2 = 6.93147180559945286227e-01;       /* 3FE62E42, FEFA39EF */
  56 
  57 double
  58 acosh(double x) {
  59         double t;
  60         int hx;
  61 
  62         hx = ((int *) &x)[HIWORD];
  63         if (hx < 0x3ff00000) {       /* x < 1 */
  64                 if (isnan(x))
  65 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
  66                         return (hx >= 0xfff80000 ? x : (x - x) / (x - x));
  67                         /* assumes sparc-like QNaN */
  68 #else