/* @(#)k_standard.c 5.1 93/09/24 */
/*
 * ====================================================
 * 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.
 * ====================================================
 */

#include <sys/cdefs.h>
#if defined(LIBM_SCCS) && !defined(lint)
__RCSID("$NetBSD: k_standard.c,v 1.23 2021/04/12 09:15:52 mrg Exp $");
#endif

#include "math.h"
#include "math_private.h"
#include <errno.h>

#ifndef _USE_WRITE
#include <stdio.h>                      /* fputs(), stderr */
#define WRITE2(u,v)     fputs(u, stderr)
#else   /* !defined(_USE_WRITE) */
#include <unistd.h>                     /* write */
#define WRITE2(u,v)     write(2, u, v)
#undef fflush
#endif  /* !defined(_USE_WRITE) */

static const double zero = 0.0; /* used as const */

/*
 * Standard conformance (non-IEEE) on exception cases.
 * Mapping:
 *      1 -- acos(|x|>1)
 *      2 -- asin(|x|>1)
 *      3 -- atan2(+-0,+-0)
 *      4 -- hypot overflow
 *      5 -- cosh overflow
 *      6 -- exp overflow
 *      7 -- exp underflow
 *      8 -- y0(0)
 *      9 -- y0(-ve)
 *      10-- y1(0)
 *      11-- y1(-ve)
 *      12-- yn(0)
 *      13-- yn(-ve)
 *      14-- lgamma(finite) overflow
 *      15-- lgamma(-integer)
 *      16-- log(0)
 *      17-- log(x<0)
 *      18-- log10(0)
 *      19-- log10(x<0)
 *      20-- pow(0.0,0.0)
 *      21-- pow(x,y) overflow
 *      22-- pow(x,y) underflow
 *      23-- pow(0,negative)
 *      24-- pow(neg,non-integral)
 *      25-- sinh(finite) overflow
 *      26-- sqrt(negative)
 *      27-- fmod(x,0)
 *      28-- remainder(x,0)
 *      29-- acosh(x<1)
 *      30-- atanh(|x|>1)
 *      31-- atanh(|x|=1)
 *      32-- scalb overflow
 *      33-- scalb underflow
 *      34-- j0(|x|>X_TLOSS)
 *      35-- y0(x>X_TLOSS)
 *      36-- j1(|x|>X_TLOSS)
 *      37-- y1(x>X_TLOSS)
 *      38-- jn(|x|>X_TLOSS, n)
 *      39-- yn(x>X_TLOSS, n)
 *      40-- gamma(finite) overflow
 *      41-- gamma(-integer)
 *      42-- pow(NaN,0.0)
 *      48-- log2(0)
 *      49-- log2(x<0)
 */


double
__kernel_standard(double x, double y, int type)
{
        struct exception exc;
#ifndef HUGE_VAL        /* this is the only routine that uses HUGE_VAL */
#define HUGE_VAL inf
        double inf = 0.0;

        SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
#endif

#ifdef _USE_WRITE
        (void) fflush(stdout);
#endif
        exc.arg1 = x;
        exc.arg2 = y;
        switch(type) {
            case 1:
            case 101:
                /* acos(|x|>1) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "acos" : "acosf";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_) {
                  exc.retval = zero/zero;
                  errno = EDOM;
                } else if (!matherr(&exc)) {
                  if(_LIB_VERSION == _SVID_) {
                    (void) WRITE2("acos: DOMAIN error\n", 19);
                  }
                  errno = EDOM;
                }
                break;
            case 2:
            case 102:
                /* asin(|x|>1) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "asin" : "asinf";
                exc.retval = zero;
                if(_LIB_VERSION == _POSIX_) {
                  exc.retval = zero/zero;
                  errno = EDOM;
                } else if (!matherr(&exc)) {
                  if(_LIB_VERSION == _SVID_) {
                        (void) WRITE2("asin: DOMAIN error\n", 19);
                  }
                  errno = EDOM;
                }
                break;
            case 3:
            case 103:
                /* atan2(+-0,+-0) */
                exc.arg1 = y;
                exc.arg2 = x;
                exc.type = DOMAIN;
                exc.name = type < 100 ? "atan2" : "atan2f";
                exc.retval = zero;
                if(_LIB_VERSION == _POSIX_) {
                  exc.retval = copysign(signbit(y) ? M_PI : zero, x);
                } else if (!matherr(&exc)) {
                  if(_LIB_VERSION == _SVID_) {
                        (void) WRITE2("atan2: DOMAIN error\n", 20);
                      }
                  errno = EDOM;
                }
                break;
            case 4:
            case 104:
                /* hypot(finite,finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "hypot" : "hypotf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 5:
            case 105:
                /* cosh(finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "cosh" : "coshf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 6:
            case 106:
                /* exp(finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "exp" : "expf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 7:
            case 107:
                /* exp(finite) underflow */
                exc.type = UNDERFLOW;
                exc.name = type < 100 ? "exp" : "expf";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 8:
            case 108:
                /* y0(0) = -inf */
                exc.type = DOMAIN;      /* should be SING for IEEE */
                exc.name = type < 100 ? "y0" : "y0f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("y0: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 9:
            case 109:
                /* y0(x<0) = NaN */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "y0" : "y0f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("y0: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 10:
            case 110:
                /* y1(0) = -inf */
                exc.type = DOMAIN;      /* should be SING for IEEE */
                exc.name = type < 100 ? "y1" : "y1f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("y1: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 11:
            case 111:
                /* y1(x<0) = NaN */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "y1" : "y1f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("y1: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 12:
            case 112:
                /* yn(n,0) = -inf */
                exc.type = DOMAIN;      /* should be SING for IEEE */
                exc.name = type < 100 ? "yn" : "ynf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("yn: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 13:
            case 113:
                /* yn(x<0) = NaN */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "yn" : "ynf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("yn: DOMAIN error\n", 17);
                      }
                  errno = EDOM;
                }
                break;
            case 14:
            case 114:
                /* lgamma(finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "lgamma" : "lgammaf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 15:
            case 115:
                /* lgamma(-integer) or lgamma(0) */
                exc.type = SING;
                exc.name = type < 100 ? "lgamma" : "lgammaf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("lgamma: SING error\n", 19);
                      }
                  errno = EDOM;
                }
                break;
            case 16:
            case 116:
                /* log(0) */
                exc.type = SING;
                exc.name = type < 100 ? "log" : "logf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log: SING error\n", 16);
                      }
                  errno = EDOM;
                }
                break;
            case 17:
            case 117:
                /* log(x<0) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "log" : "logf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log: DOMAIN error\n", 18);
                      }
                  errno = EDOM;
                }
                break;
            case 18:
            case 118:
                /* log10(0) */
                exc.type = SING;
                exc.name = type < 100 ? "log10" : "log10f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log10: SING error\n", 18);
                      }
                  errno = EDOM;
                }
                break;
            case 19:
            case 119:
                /* log10(x<0) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "log10" : "log10f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log10: DOMAIN error\n", 20);
                      }
                  errno = EDOM;
                }
                break;
            case 20:
            case 120:
                /* pow(0.0,0.0) */
                /* error only if _LIB_VERSION == _SVID_ */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "pow" : "powf";
                exc.retval = zero;
                if (_LIB_VERSION != _SVID_) exc.retval = 1.0;
                else if (!matherr(&exc)) {
                        (void) WRITE2("pow(0,0): DOMAIN error\n", 23);
                        errno = EDOM;
                }
                break;
            case 21:
            case 121:
                /* pow(x,y) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "pow" : "powf";
                if (_LIB_VERSION == _SVID_) {
                  exc.retval = HUGE;
                  y *= 0.5;
                  if(x<zero&&rint(y)!=y) exc.retval = -HUGE;
                } else {
                  exc.retval = HUGE_VAL;
                  y *= 0.5;
                  if(x<zero&&rint(y)!=y) exc.retval = -HUGE_VAL;
                }
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 22:
            case 122:
                /* pow(x,y) underflow */
                exc.type = UNDERFLOW;
                exc.name = type < 100 ? "pow" : "powf";
                exc.retval =  zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 23:
            case 123:
                /* 0**neg */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "pow" : "powf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = zero;
                else {
                  exc.retval = HUGE_VAL;
                  y *= 0.5;
                  if(signbit(x)&&rint(y)!=y) exc.retval = -HUGE_VAL;
                }
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("pow(0,neg): DOMAIN error\n", 25);
                      }
                  errno = EDOM;
                }
                break;
            case 24:
            case 124:
                /* neg**non-integral */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "pow" : "powf";
                if (_LIB_VERSION == _SVID_)
                    exc.retval = zero;
                else
                    exc.retval = zero/zero;     /* X/Open allow NaN */
                if (_LIB_VERSION == _POSIX_)
                   errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("neg**non-integral: DOMAIN error\n", 32);
                      }
                  errno = EDOM;
                }
                break;
            case 25:
            case 125:
                /* sinh(finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "sinh" : "sinhf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = ( (x>zero) ? HUGE : -HUGE);
                else
                  exc.retval = ( (x>zero) ? HUGE_VAL : -HUGE_VAL);
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 26:
            case 126:
            case 226:
                /* sqrt(x<0) */
                exc.type = DOMAIN;
                if (type == 26)
                        exc.name = "sqrt";
                else if (type == 126)
                        exc.name = "sqrtf";
                else
                        exc.name = "sqrtl";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = zero;
                else
                  exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("sqrt: DOMAIN error\n", 19);
                      }
                  errno = EDOM;
                }
                break;
            case 27:
            case 127:
            case 227:
                /* fmod(x,0) */
                exc.type = DOMAIN;
                if (type == 27)
                        exc.name = "fmod";
                else if (type == 127)
                        exc.name = "fmodf";
                else
                        exc.name = "fmodl";
                if (_LIB_VERSION == _SVID_)
                    exc.retval = x;
                else
                    exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                    (void) WRITE2("fmod:  DOMAIN error\n", 20);
                  }
                  errno = EDOM;
                }
                break;
            case 28:
            case 128:
                /* remainder(x,0) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "remainder" : "remainderf";
                exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                    (void) WRITE2("remainder: DOMAIN error\n", 24);
                  }
                  errno = EDOM;
                }
                break;
            case 29:
            case 129:
                /* acosh(x<1) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "acosh" : "acoshf";
                exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                    (void) WRITE2("acosh: DOMAIN error\n", 20);
                  }
                  errno = EDOM;
                }
                break;
            case 30:
            case 130:
                /* atanh(|x|>1) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "atanh" : "atanhf";
                exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                    (void) WRITE2("atanh: DOMAIN error\n", 20);
                  }
                  errno = EDOM;
                }
                break;
            case 31:
            case 131:
                /* atanh(|x|=1) */
                exc.type = SING;
                exc.name = type < 100 ? "atanh" : "atanhf";
                exc.retval = x/zero;    /* sign(x)*inf */
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                    (void) WRITE2("atanh: SING error\n", 18);
                  }
                  errno = EDOM;
                }
                break;
            case 32:
            case 132:
                /* scalb overflow; SVID also returns +-HUGE_VAL */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "scalb" : "scalbf";
                exc.retval = x > zero ? HUGE_VAL : -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 33:
            case 133:
                /* scalb underflow */
                exc.type = UNDERFLOW;
                exc.name = type < 100 ? "scalb" : "scalbf";
                exc.retval = copysign(zero,x);
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                        errno = ERANGE;
                }
                break;
            case 34:
            case 134:
                /* j0(|x|>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "j0" : "j0f";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 35:
            case 135:
                /* y0(x>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "y0" : "y0f";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 36:
            case 136:
                /* j1(|x|>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "j1" : "j1f";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 37:
            case 137:
                /* y1(x>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "y1" : "y1f";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 38:
            case 138:
                /* jn(|x|>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "jn" : "jnf";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 39:
            case 139:
                /* yn(x>X_TLOSS) */
                exc.type = TLOSS;
                exc.name = type < 100 ? "yn" : "ynf";
                exc.retval = zero;
                if (_LIB_VERSION == _POSIX_)
                        errno = ERANGE;
                else if (!matherr(&exc)) {
                        if (_LIB_VERSION == _SVID_) {
                                (void) WRITE2(exc.name, 2);
                                (void) WRITE2(": TLOSS error\n", 14);
                        }
                        errno = ERANGE;
                }
                break;
            case 40:
            case 140:
                /* gamma(finite) overflow */
                exc.type = OVERFLOW;
                exc.name = type < 100 ? "gamma" : "gammaf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                  errno = ERANGE;
                }
                break;
            case 41:
            case 141:
                /* gamma(-integer) or gamma(0) */
                exc.type = SING;
                exc.name = type < 100 ? "gamma" : "gammaf";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = HUGE;
                else
                  exc.retval = HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("gamma: SING error\n", 18);
                      }
                  errno = EDOM;
                }
                break;
            case 42:
            case 142:
                /* pow(NaN,0.0) */
                /* error only if _LIB_VERSION == _SVID_ & _XOPEN_ */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "pow" : "powf";
                exc.retval = x;
                if (_LIB_VERSION == _IEEE_ ||
                    _LIB_VERSION == _POSIX_) exc.retval = 1.0;
                else if (!matherr(&exc)) {
                        errno = EDOM;
                }
                break;
            case 48:
            case 148:
                /* log2(0) */
                exc.type = SING;
                exc.name = type < 100 ? "log2" : "log2f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                if (_LIB_VERSION == _POSIX_)
                  errno = ERANGE;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log2: SING error\n", 18);
                      }
                  errno = EDOM;
                }
                break;
            case 49:
            case 149:
                /* log2(x<0) */
                exc.type = DOMAIN;
                exc.name = type < 100 ? "log2" : "log2f";
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = zero/zero;
                if (_LIB_VERSION == _POSIX_)
                  errno = EDOM;
                else if (!matherr(&exc)) {
                  if (_LIB_VERSION == _SVID_) {
                        (void) WRITE2("log2: DOMAIN error\n", 20);
                      }
                  errno = EDOM;
                }
                break;
            default:
                if (_LIB_VERSION == _SVID_)
                  exc.retval = -HUGE;
                else
                  exc.retval = -HUGE_VAL;
                errno = EDOM;
                break;
        }
        return exc.retval;
}