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| author | Szabolcs Nagy <nsz@port70.net> | 2012-12-11 23:56:59 +0100 |
|---|---|---|
| committer | Szabolcs Nagy <nsz@port70.net> | 2012-12-11 23:56:59 +0100 |
| commit | b12a73d5bf595b7fbb73db30c6bb144078e86ef5 (patch) | |
| tree | 547edc4ee13453230bb1c154015150b9fc88c766 /src/math/atanl.c | |
| parent | 482ccd2f7497a79ca83e998f54e823e7cedaaa6e (diff) | |
| download | musl-b12a73d5bf595b7fbb73db30c6bb144078e86ef5.tar.gz musl-b12a73d5bf595b7fbb73db30c6bb144078e86ef5.tar.xz musl-b12a73d5bf595b7fbb73db30c6bb144078e86ef5.zip | |
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
Diffstat (limited to 'src/math/atanl.c')
| -rw-r--r-- | src/math/atanl.c | 33 |
1 files changed, 13 insertions, 20 deletions
diff --git a/src/math/atanl.c b/src/math/atanl.c index 33ecff0d..6a480a7a 100644 --- a/src/math/atanl.c +++ b/src/math/atanl.c @@ -22,11 +22,6 @@ long double atanl(long double x) return atan(x); } #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 -#include "__invtrigl.h" - -#define ATAN_CONST (BIAS + 65) /* 2**65 */ -#define ATAN_LINEAR (BIAS - 32) /* 2**-32 */ -static const long double huge = 1.0e300; static const long double atanhi[] = { 4.63647609000806116202e-01L, @@ -81,29 +76,27 @@ long double atanl(long double x) u.e = x; expsign = u.xbits.expsign; expt = expsign & 0x7fff; - if (expt >= ATAN_CONST) { /* if |x| is large, atan(x)~=pi/2 */ - if (expt == BIAS + LDBL_MAX_EXP && + if (expt >= 0x3fff + 65) { /* if |x| is large, atan(x)~=pi/2 */ + if (expt == 0x7fff && ((u.bits.manh&~LDBL_NBIT)|u.bits.manl)!=0) /* NaN */ return x+x; - if (expsign > 0) - return atanhi[3]+atanlo[3]; - else - return -atanhi[3]-atanlo[3]; + z = atanhi[3] + 0x1p-1000; + return expsign < 0 ? -z : z; } /* Extract the exponent and the first few bits of the mantissa. */ /* XXX There should be a more convenient way to do this. */ - expman = (expt << 8) | ((u.bits.manh >> (MANH_SIZE - 9)) & 0xff); - if (expman < ((BIAS - 2) << 8) + 0xc0) { /* |x| < 0.4375 */ - if (expt < ATAN_LINEAR) { /* if |x| is small, atanl(x)~=x */ - /* raise inexact */ - if (huge+x > 1.0) - return x; + expman = (expt << 8) | ((u.bits.manh >> (LDBL_MANH_SIZE - 9)) & 0xff); + if (expman < ((0x3fff - 2) << 8) + 0xc0) { /* |x| < 0.4375 */ + if (expt < 0x3fff - 32) { /* if |x| is small, atanl(x)~=x */ + /* raise inexact if x!=0 */ + FORCE_EVAL(x + 0x1p1000); + return x; } id = -1; } else { x = fabsl(x); - if (expman < (BIAS << 8) + 0x30) { /* |x| < 1.1875 */ - if (expman < ((BIAS - 1) << 8) + 0x60) { /* 7/16 <= |x| < 11/16 */ + if (expman < (0x3fff << 8) + 0x30) { /* |x| < 1.1875 */ + if (expman < ((0x3fff - 1) << 8) + 0x60) { /* 7/16 <= |x| < 11/16 */ id = 0; x = (2.0*x-1.0)/(2.0+x); } else { /* 11/16 <= |x| < 19/16 */ @@ -111,7 +104,7 @@ long double atanl(long double x) x = (x-1.0)/(x+1.0); } } else { - if (expman < ((BIAS + 1) << 8) + 0x38) { /* |x| < 2.4375 */ + if (expman < ((0x3fff + 1) << 8) + 0x38) { /* |x| < 2.4375 */ id = 2; x = (x-1.5)/(1.0+1.5*x); } else { /* 2.4375 <= |x| < 2^ATAN_CONST */ |