summaryrefslogtreecommitdiff
path: root/src/math/acosl.c
diff options
context:
space:
mode:
authorSzabolcs Nagy <nsz@port70.net>2012-12-11 23:56:59 +0100
committerSzabolcs Nagy <nsz@port70.net>2012-12-11 23:56:59 +0100
commitb12a73d5bf595b7fbb73db30c6bb144078e86ef5 (patch)
tree547edc4ee13453230bb1c154015150b9fc88c766 /src/math/acosl.c
parent482ccd2f7497a79ca83e998f54e823e7cedaaa6e (diff)
downloadmusl-b12a73d5bf595b7fbb73db30c6bb144078e86ef5.tar.gz
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/acosl.c')
-rw-r--r--src/math/acosl.c61
1 files changed, 26 insertions, 35 deletions
diff --git a/src/math/acosl.c b/src/math/acosl.c
index 83857d49..9e9b01e4 100644
--- a/src/math/acosl.c
+++ b/src/math/acosl.c
@@ -23,55 +23,46 @@ long double acosl(long double x)
}
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
#include "__invtrigl.h"
-#define ACOS_CONST (BIAS - 65) /* 2**-65 */
long double acosl(long double x)
{
union IEEEl2bits u;
- long double z, p, q, r, w, s, c, df;
+ long double z, w, s, c, df;
int16_t expsign, expt;
u.e = x;
expsign = u.xbits.expsign;
expt = expsign & 0x7fff;
- if (expt >= BIAS) { /* |x| >= 1 */
- if (expt == BIAS &&
+ /* |x| >= 1 or nan */
+ if (expt >= 0x3fff) {
+ if (expt == 0x3fff &&
((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) {
if (expsign > 0)
- return 0.0; /* acos(1) = 0 */
- else
- // FIXME
- return pi_hi + 2.0 * pio2_lo; /* acos(-1)= pi */
+ return 0; /* acos(1) = 0 */
+ return 2*pio2_hi + 0x1p-1000; /* acos(-1)= pi */
}
- return (x - x) / (x - x); /* acos(|x|>1) is NaN */
+ return 0/(x-x); /* acos(|x|>1) is NaN */
}
- if (expt < BIAS - 1) { /* |x| < 0.5 */
- if (expt < ACOS_CONST)
- return pio2_hi + pio2_lo; /* x tiny: acosl=pi/2 */
- z = x * x;
- p = P(z);
- q = Q(z);
- r = p / q;
- return pio2_hi - (x - (pio2_lo - x * r));
- } else if (expsign < 0) { /* x < -0.5 */
+ /* |x| < 0.5 */
+ if (expt < 0x3fff - 1) {
+ if (expt < 0x3fff - 65)
+ return pio2_hi + 0x1p-1000; /* x < 0x1p-65: acosl(x)=pi/2 */
+ return pio2_hi - (x - (pio2_lo - x * __invtrigl_R(x*x)));
+ }
+ /* x < -0.5 */
+ if (expsign < 0) {
z = (1.0 + x) * 0.5;
- p = P(z);
- q = Q(z);
- s = sqrtl(z);
- r = p / q;
- w = r * s - pio2_lo;
- return pi_hi - 2.0 * (s + w);
- } else { /* x > 0.5 */
- z = (1.0 - x) * 0.5;
s = sqrtl(z);
- u.e = s;
- u.bits.manl = 0;
- df = u.e;
- c = (z - df * df) / (s + df);
- p = P(z);
- q = Q(z);
- r = p / q;
- w = r * s + c;
- return 2.0 * (df + w);
+ w = __invtrigl_R(z) * s - pio2_lo;
+ return 2*(pio2_hi - (s + w));
}
+ /* x > 0.5 */
+ z = (1.0 - x) * 0.5;
+ s = sqrtl(z);
+ u.e = s;
+ u.bits.manl = 0;
+ df = u.e;
+ c = (z - df * df) / (s + df);
+ w = __invtrigl_R(z) * s + c;
+ return 2*(df + w);
}
#endif