/*?Test?of?the?double?rounding?effect.
?*
?*?This?example?was?presented?at?the?CNC‘2?summer?school?on?MPFR?and?MPC
?*?at?LORIA?Nancy?France.
?*
?*?Arguments:?max?difference?of?exponents?dmax?significand?size?n.
?*?Optional?argument:?extended?precision?p?（with?double?rounding）.
?*
?*?Return?all?the?couples?of?positive?machine?numbers?（xy）?such?that
?*?1/2?<=?y??*?in?precision?n?and?the?results?of?floor（x/y）?in?the?rounding?modes
?*?toward?0?and?to?nearest?are?different.
?*/

/*
Copyright?2009?Free?Software?Foundation?Inc.
Contributed?by?the?Arenaire?and?Cacao?projects?INRIA.

This?file?is?part?of?the?GNU?MPFR?Library.

The?GNU?MPFR?Library?is?free?software;?you?can?redistribute?it?and/or?modify
it?under?the?terms?of?the?GNU?Lesser?General?Public?License?as?published?by
the?Free?Software?Foundation;?either?version?2.1?of?the?License?or?（at?your
option）?any?later?version.

The?GNU?MPFR?Library?is?distributed?in?the?hope?that?it?will?be?useful?but
WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of?MERCHANTABILITY
or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the?GNU?Lesser?General?Public
License?for?more?details.

You?should?have?received?a?copy?of?the?GNU?Lesser?General?Public?License
along?with?the?GNU?MPFR?Library;?see?the?file?COPYING.LIB.??If?not?write?to
the?Free?Software?Foundation?Inc.?51?Franklin?St?Fifth?Floor?Boston
MA?02110-1301?USA.
*/

#include?
#include?
#include?

#define?PRECN?x?y?z
#define?VARS?PRECN?t

static?unsigned?long
eval?（mpfr_t?x?mpfr_t?y?mpfr_t?z?mpfr_t?t?mpfr_rnd_t?rnd）
{
??mpfr_div?（t?x?y?rnd）;??/*?the?division?x/y?in?precision?p?*/
??mpfr_set?（z?t?rnd）;?????/*?the?rounding?to?the?precision?n?*/
??mpfr_rint_floor?（z?z?rnd）;
??return?mpfr_get_ui?（z?rnd）;
}

int?main?（int?argc?char?*argv[]）
{
??int?dmax?n?p;
??mpfr_t?VARS;

??if?（argc?!=?3?&&?argc?!=?4）
????{
??????fprintf?（stderr?“Usage:?divworst???[?
?]\n“）;
??????exit?（EXIT_FAILURE）;
????}

??dmax?=?atoi?（argv[1]）;
??n?=?atoi?（argv[2]）;
??p?=?argc?==?3???n?:?atoi?（argv[3]）;
??if?（p?????{
??????fprintf?（stderr?“divworst:?p?must?be?greater?or?equal?to?n\n“）;
??????exit?（EXIT_FAILURE）;
????}

??mpfr_inits2?（n?PRECN?（mpfr_ptr）?0）;
??mpfr_init2?（t?p）;

??for?（mpfr_set_ui_2exp?（x?1?-1?GMP_RNDN）;
???????mpfr_get_exp?（x）?<=?dmax;
???????mpfr_nextabove?（x））
????for?（mpfr_set_ui_2exp?（y?1?-1?GMP_RNDN）;
?????????mpfr_get_exp?（y）?==?0;
?????????mpfr_nextabove?（y））
??????{
????????unsigned?long?rz?rn;

????????if?（mpfr_sub?（z?x?y?GMP_RNDZ）?!=?0）
??????????continue;??/*?x?-?y?is?not?representable?in?precision?n?*/
????????rz?=?eval?（x?y?z?t?GMP_RNDZ）;
????????rn?=?eval?（x?y?z?t?GMP_RNDN）;
????????if?（rz?==?rn）
??????????continue;
????????mpfr_printf?（“x?=?%.*Rb?;?y?=?%.*Rb?;?Z:?%lu?;?N:?%lu\n“
?????????????????????n?-?1?x?n?-?1?y?rz?rn）;
??????}

??mpfr_clears?（VARS?（mpfr_ptr）?0）;
??return?0;
}