diff options
| author | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2007-06-28 11:54:41 +0000 |
|---|---|---|
| committer | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2007-06-28 11:54:41 +0000 |
| commit | 8d5f44e87eff5f213762fa096be2cc3a9b48a050 (patch) | |
| tree | ad3d90ac8c7094f91d40349125beb6ba611c07a1 /cot.c | |
| parent | eafe839ea1ae31ba32c6c622713a1f7e081a0814 (diff) | |
| download | mpfr-8d5f44e87eff5f213762fa096be2cc3a9b48a050.tar.gz | |
cot.c: use MPFR_SAVE_EXPO_UPDATE_FLAGS, but the case +/- 2^emin could
still be buggy with the current code; added a MPFR_ASSERTN (0) until
it is implemented.
BUGS: updated item on mpfr_cot.
git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@4575 280ebfd0-de03-0410-8827-d642c229c3f4
Diffstat (limited to 'cot.c')
| -rw-r--r-- | cot.c | 15 |
1 files changed, 14 insertions, 1 deletions
@@ -45,11 +45,20 @@ MA 02110-1301, USA. */ Since |cot(x) - 1/x| <= 0.36, if 2^(-2n) ufp(y) >= 0.72, then |y - cot(x)| >= 2^(-2n-1) ufp(y), and rounding 1/x gives the correct result. If x < 2^E, then y > 2^(-E), thus ufp(y) > 2^(-E-1). - A sufficient condition is thus EXP(x) + 1 <= -2 MAX(PREC(x),PREC(Y)). */ + A sufficient condition is thus EXP(x) + 1 <= -2 MAX(PREC(x),PREC(Y)). + The division can be inexact in case of underflow or overflow; but + an underflow is not possible as emin = - emax. The overflow is a + real overflow possibly except when |x| = 2^emin. */ #define ACTION_TINY(y,x,r) \ if (MPFR_EXP(x) + 1 <= -2 * (mp_exp_t) MAX(MPFR_PREC(x), MPFR_PREC(y))) \ { \ int signx = MPFR_SIGN(x); \ + if (mpfr_get_exp (x) == __gmpfr_emin+1 && \ + mpfr_powerof2_raw (x)) \ + { \ + /* Case |x| = 2^emin. */ \ + MPFR_ASSERTN (0); /* TODO (and add test) */ \ + } \ inexact = mpfr_ui_div (y, 1, x, r); \ if (inexact == 0) /* x is a power of two */ \ { /* result always 1/x, except when rounding to zero */ \ @@ -68,6 +77,10 @@ MA 02110-1301, USA. */ else /* round to nearest */ \ inexact = signx; \ } \ + MPFR_ASSERTN (MPFR_EMIN_MIN + MPFR_EMAX_MAX == 0); \ + /* Underflow is not possible with emin = - emax. */ \ + MPFR_ASSERTN (! mpfr_underflow_p ()); \ + MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags); \ goto end; \ } |