ilogb

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Langue: ja

Version: 2004-10-31 (openSuse - 09/10/07)

Section: 3 (Bibliothèques de fonctions)

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ilogb, ilogbf, ilogbl - ÉâÆ°¾®¿ôÅÀ¿ô¤ÎÀ°¿ô¤Î»Ø¿ô¤ò¼èÆÀ¤¹¤ë

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#include <math.h>

int ilogb(double x);
int ilogbf(float x);
int ilogbl(long double x);

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¥¨¥é¡¼¤¬µ¯¤­¤Æ¤¤¤Æ¡¢¤«¤Ä (math_errhandling & MATH_ERRNO) ¤¬ 0 °Ê³°¤Î¾ì¹ç¡¢ errno ¤¬ EDOM ¤ËÀßÄꤵ¤ì¤ë¡£ ¥¨¥é¡¼¤¬µ¯¤­¤Æ¤¤¤Æ¡¢¤«¤Ä (math_errhandling & MATH_ERREXCEPT) ¤¬ 0 °Ê³°¤Î¾ì¹ç¡¢ÉÔÀµ¤ÊÉâÆ°¾®¿ôÅÀ¿ô¤Ë¤è¤ëÎã³°¤¬È¯À¸¤¹¤ë¡£

x ¤¬ 0, ̵¸ÂÂç (Â礭¤¹¤®¤ë¡¢¾®¤µ¤¹¤®¤ë), NaN ¤Î¾ì¹ç¡¢ ÄêµÁ°è (domain) ¥¨¥é¡¼¤¬µ¯¤ë¡£ x ¤¬ 0 ¤Î¾ì¹ç¡¢Äê¿ô FP_ILOGB0 ¤¬ÊÖ¤µ¤ì¤ë¡£ x ¤¬ NaN ¤Î¾ì¹ç¡¢Äê¿ô FP_ILOGBNAN ¤¬ÊÖ¤µ¤ì¤ë¡£ x ¤¬Ìµ¸ÂÂç¤Î¾ì¹ç (¤Þ¤¿¤ÏÂ礭¤¹¤®¤ë¾ì¹ç)¡¢INT_MAX ¤¬ÊÖ¤µ¤ì¤ë¡£ x ¤¬¾®¤µ¤¹¤®¤ë¾ì¹ç¡¢INT_MIN ¤¬ÊÖ¤µ¤ì¤ë¡£

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log(3), logb(3)