From b12a73d5bf595b7fbb73db30c6bb144078e86ef5 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Tue, 11 Dec 2012 23:56:59 +0100 Subject: math: clean up inverse trigonometric functions modifications: * avoid unsigned->signed conversions * removed various volatile hacks * use FORCE_EVAL when evaluating only for side-effects * factor out R() rational approximation instead of manual inline * __invtrigl.h now only provides __invtrigl_R, __pio2_hi and __pio2_lo * use 2*pio2_hi, 2*pio2_lo instead of pi_hi, pi_lo otherwise the logic is not changed, long double versions will need a revisit when a genaral long double cleanup happens --- src/math/atan2l.c | 40 +++++++++++++++++++--------------------- 1 file changed, 19 insertions(+), 21 deletions(-) (limited to 'src/math/atan2l.c') diff --git a/src/math/atan2l.c b/src/math/atan2l.c index 45cbfcc1..e86dbffb 100644 --- a/src/math/atan2l.c +++ b/src/math/atan2l.c @@ -24,8 +24,6 @@ long double atan2l(long double y, long double x) } #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 #include "__invtrigl.h" -// FIXME: -static const volatile long double tiny = 1.0e-300; long double atan2l(long double y, long double x) { @@ -40,12 +38,12 @@ long double atan2l(long double y, long double x) ux.e = x; expsignx = ux.xbits.expsign; exptx = expsignx & 0x7fff; - if ((exptx==BIAS+LDBL_MAX_EXP && + if ((exptx==0x7fff && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)!=0) || /* x is NaN */ - (expty==BIAS+LDBL_MAX_EXP && + (expty==0x7fff && ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)!=0)) /* y is NaN */ return x+y; - if (expsignx==BIAS && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0) /* x=1.0 */ + if (expsignx==0x3fff && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0) /* x=1.0 */ return atanl(y); m = ((expsigny>>15)&1) | ((expsignx>>14)&2); /* 2*sign(x)+sign(y) */ @@ -54,39 +52,39 @@ long double atan2l(long double y, long double x) switch(m) { case 0: case 1: return y; /* atan(+-0,+anything)=+-0 */ - case 2: return pi_hi+tiny; /* atan(+0,-anything) = pi */ - case 3: return -pi_hi-tiny; /* atan(-0,-anything) =-pi */ + case 2: return 2*pio2_hi+0x1p-1000; /* atan(+0,-anything) = pi */ + case 3: return -2*pio2_hi-0x1p-1000; /* atan(-0,-anything) =-pi */ } } /* when x = 0 */ if (exptx==0 && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0) - return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny; + return expsigny < 0 ? -pio2_hi-0x1p-1000 : pio2_hi+0x1p-1000; /* when x is INF */ - if (exptx == BIAS+LDBL_MAX_EXP) { - if (expty == BIAS+LDBL_MAX_EXP) { + if (exptx == 0x7fff) { + if (expty == 0x7fff) { switch(m) { - case 0: return pio2_hi*0.5+tiny; /* atan(+INF,+INF) */ - case 1: return -pio2_hi*0.5-tiny; /* atan(-INF,+INF) */ - case 2: return 1.5*pio2_hi+tiny; /* atan(+INF,-INF) */ - case 3: return -1.5*pio2_hi-tiny; /* atan(-INF,-INF) */ + case 0: return pio2_hi*0.5+0x1p-1000; /* atan(+INF,+INF) */ + case 1: return -pio2_hi*0.5-0x1p-1000; /* atan(-INF,+INF) */ + case 2: return 1.5*pio2_hi+0x1p-1000; /* atan(+INF,-INF) */ + case 3: return -1.5*pio2_hi-0x1p-1000; /* atan(-INF,-INF) */ } } else { switch(m) { case 0: return 0.0; /* atan(+...,+INF) */ case 1: return -0.0; /* atan(-...,+INF) */ - case 2: return pi_hi+tiny; /* atan(+...,-INF) */ - case 3: return -pi_hi-tiny; /* atan(-...,-INF) */ + case 2: return 2*pio2_hi+0x1p-1000; /* atan(+...,-INF) */ + case 3: return -2*pio2_hi-0x1p-1000; /* atan(-...,-INF) */ } } } /* when y is INF */ - if (expty == BIAS+LDBL_MAX_EXP) - return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny; + if (expty == 0x7fff) + return expsigny < 0 ? -pio2_hi-0x1p-1000 : pio2_hi+0x1p-1000; /* compute y/x */ k = expty-exptx; if(k > LDBL_MANT_DIG+2) { /* |y/x| huge */ - z = pio2_hi+pio2_lo; + z = pio2_hi+0x1p-1000; m &= 1; } else if (expsignx < 0 && k < -LDBL_MANT_DIG-2) /* |y/x| tiny, x<0 */ z = 0.0; @@ -95,9 +93,9 @@ long double atan2l(long double y, long double x) switch (m) { case 0: return z; /* atan(+,+) */ case 1: return -z; /* atan(-,+) */ - case 2: return pi_hi-(z-pi_lo); /* atan(+,-) */ + case 2: return 2*pio2_hi-(z-2*pio2_lo); /* atan(+,-) */ default: /* case 3 */ - return (z-pi_lo)-pi_hi; /* atan(-,-) */ + return (z-2*pio2_lo)-2*pio2_hi; /* atan(-,-) */ } } #endif -- cgit v1.2.1