381 lines
13 KiB
HTML
381 lines
13 KiB
HTML
<HTML><HEAD><TITLE><float.h></TITLE></HEAD><BODY BGCOLOR="#FFFFFF">
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<H1><A NAME="<float.h>"><CODE><float.h></CODE></A></H1><HR>
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<P><CODE>
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#define <A HREF="#DBL_DIG"><B>DBL_DIG</B></A>
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<I><integer rvalue >= 10></I><BR>
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#define <A HREF="#DBL_EPSILON"><B>DBL_EPSILON</B></A>
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<I><double rvalue <= 10^(-9)></I><BR>
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#define <A HREF="#DBL_MANT_DIG"><B>DBL_MANT_DIG</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#DBL_MAX"><B>DBL_MAX</B></A>
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<I><double rvalue >= 10^37></I><BR>
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#define <A HREF="#DBL_MAX_10_EXP"><B>DBL_MAX_10_EXP</B></A>
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<I><integer rvalue >= 37></I><BR>
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#define <A HREF="#DBL_MAX_EXP"><B>DBL_MAX_EXP</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#DBL_MIN"><B>DBL_MIN</B></A>
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<I><double rvalue <= 10^(-37)></I><BR>
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#define <A HREF="#DBL_MIN_10_EXP"><B>DBL_MIN_10_EXP</B></A>
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<I><integer rvalue <= -37></I><BR>
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#define <A HREF="#DBL_MIN_EXP"><B>DBL_MIN_EXP</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#FLT_DIG"><B>FLT_DIG</B></A>
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<I><integer rvalue >= 6></I><BR>
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#define <A HREF="#FLT_EPSILON"><B>FLT_EPSILON</B></A>
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<I><float rvalue <= 10^(-5)></I><BR>
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#define <A HREF="#FLT_MANT_DIG"><B>FLT_MANT_DIG</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#FLT_MAX"><B>FLT_MAX</B></A>
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<I><float rvalue >= 10^37></I><BR>
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#define <A HREF="#FLT_MAX_10_EXP"><B>FLT_MAX_10_EXP</B></A>
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<I><integer rvalue >= 37></I><BR>
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#define <A HREF="#FLT_MAX_EXP"><B>FLT_MAX_EXP</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#FLT_MIN"><B>FLT_MIN</B></A>
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<I><float rvalue <= 10^(-37)></I><BR>
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#define <A HREF="#FLT_MIN_10_EXP"><B>FLT_MIN_10_EXP</B></A>
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<I><integer rvalue <= -37></I><BR>
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#define <A HREF="#FLT_MIN_EXP"><B>FLT_MIN_EXP</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#FLT_RADIX"><B>FLT_RADIX</B></A>
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<I><#if expression >= 2></I><BR>
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#define <A HREF="#FLT_ROUNDS"><B>FLT_ROUNDS</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#LDBL_DIG"><B>LDBL_DIG</B></A>
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<I><integer rvalue >= 10></I><BR>
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#define <A HREF="#LDBL_EPSILON"><B>LDBL_EPSILON</B></A>
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<I><long double rvalue <= 10^(-9)></I><BR>
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#define <A HREF="#LDBL_MANT_DIG"><B>LDBL_MANT_DIG</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#LDBL_MAX"><B>LDBL_MAX</B></A>
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<I><long double rvalue >= 10^37></I><BR>
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#define <A HREF="#LDBL_MAX_10_EXP"><B>LDBL_MAX_10_EXP</B></A>
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<I><integer rvalue >= 37></I><BR>
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#define <A HREF="#LDBL_MAX_EXP"><B>LDBL_MAX_EXP</B></A>
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<I><integer rvalue></I><BR>
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#define <A HREF="#LDBL_MIN"><B>LDBL_MIN</B></A>
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<I><long double rvalue <= 10^(-37)></I><BR>
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#define <A HREF="#LDBL_MIN_10_EXP"><B>LDBL_MIN_10_EXP</B></A>
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<I><integer rvalue <= -37></I><BR>
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#define <A HREF="#LDBL_MIN_EXP"><B>LDBL_MIN_EXP</B></A>
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<I><integer rvalue></I>
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</CODE></P>
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<P>Include the standard header <B><CODE><float.h></CODE></B>
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to determine various properties of floating-point type representations.
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The standard header <CODE><float.h></CODE> is available even in a
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<A HREF="lib_over.html#freestanding implementation" tppabs="http://ccs.ucsd.edu/c/lib_over.html#freestanding implementation">
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freestanding implementation</A>.</P>
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<P>You can test only the value of the macro
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A> in an
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<A HREF="preproc.html#if directive" tppabs="http://ccs.ucsd.edu/c/preproc.html#if directive"><I>if</I> directive</A>.
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(The macro expands to a
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<A HREF="preproc.html#if expression" tppabs="http://ccs.ucsd.edu/c/preproc.html#if expression"><I><I>#if</I> expression</A>.)
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All other macros defined in this header expand to expressions whose
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values can be determined only when the program executes. (These macros are
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<A HREF="express.html#rvalue expression" tppabs="http://ccs.ucsd.edu/c/express.html#rvalue expression">rvalue expressions</A>.)
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Some target environments can change
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the rounding and error-reporting properties of floating-point type
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representations while the program is running.</P>
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<H2><A NAME="DBL_DIG"><CODE>DBL_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_DIG</B> <I><integer rvalue >= 10></I>
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</CODE></P>
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<P>The macro yields the precision in decimal digits for
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type <I>double.</I></P>
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<H2><A NAME="DBL_EPSILON"><CODE>DBL_EPSILON</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_EPSILON</B> <I><double rvalue <= 10^(-9)></I>
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</CODE></P>
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<P>The macro yields the smallest <I>X</I> of type <I>double</I>
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such that 1.0 + <I>X</I> != 1.0.</P>
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<H2><A NAME="DBL_MANT_DIG"><CODE>DBL_MANT_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MANT_DIG</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the number of mantissa digits, base
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>,
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for type <I>double.</I></P>
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<H2><A NAME="DBL_MAX"><CODE>DBL_MAX</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MAX</B> <I><double rvalue >= 10^37></I>
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</CODE></P>
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<P>The macro yields the largest finite representable value
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of type <I>double.</I></P>
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<H2><A NAME="DBL_MAX_10_EXP"><CODE>DBL_MAX_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MAX_10_EXP</B> <I><integer rvalue >= 37></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that
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10^<I>X</I> is a finite representable value of type <I>double.</I></P>
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<H2><A NAME="DBL_MAX_EXP"><CODE>DBL_MAX_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MAX_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a finite representable value of type <I>double.</I></P>
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<H2><A NAME="DBL_MIN"><CODE>DBL_MIN</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MIN</B> <I><double rvalue <= 10^(-37)></I>
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</CODE></P>
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<P>The macro yields the smallest normalized, finite representable
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value of type <I>double.</I></P>
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<H2><A NAME="DBL_MIN_10_EXP"><CODE>DBL_MIN_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MIN_10_EXP</B> <I><integer rvalue <= -37></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X</I> such that
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10^<I>X</I> is a normalized, finite representable value
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of type <I>double.</I></P>
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<H2><A NAME="DBL_MIN_EXP"><CODE>DBL_MIN_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>DBL_MIN_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a normalized, finite representable value of type <I>double.</I></P>
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<H2><A NAME="FLT_DIG"><CODE>FLT_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_DIG</B> <I><integer rvalue >= 6></I>
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</CODE></P>
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<P>The macro yields the precision in decimal digits
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for type <I>float.</I></P>
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<H2><A NAME="FLT_EPSILON"><CODE>FLT_EPSILON</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_EPSILON</B> <I><float rvalue <= 10^(-5)></I>
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</CODE></P>
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<P>The macro yields the smallest <I>X</I> of type <I>float</I>
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such that 1.0 + <I>X</I> != 1.0.</P>
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<H2><A NAME="FLT_MANT_DIG"><CODE>FLT_MANT_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MANT_DIG</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the number of mantissa digits, base
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>,
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for type <I>float.</I></P>
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<H2><A NAME="FLT_MAX"><CODE>FLT_MAX</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MAX</B> <I><float rvalue >= 10^37></I>
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</CODE></P>
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<P>The macro yields the largest finite representable value
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of type <I>float.</I></P>
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<H2><A NAME="FLT_MAX_10_EXP"><CODE>FLT_MAX_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MAX_10_EXP</B> <I><integer rvalue >= 37></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that 10^<I>X</I>
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is a finite representable value of type <I>float.</I></P>
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<H2><A NAME="FLT_MAX_EXP"><CODE>FLT_MAX_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MAX_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a finite representable value of type <I>float.</I></P>
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<H2><A NAME="FLT_MIN"><CODE>FLT_MIN</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MIN</B> <I><float rvalue <= 10^(-37)></I>
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</CODE></P>
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<P>The macro yields the smallest normalized, finite representable
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value of type <I>float.</I></P>
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<H2><A NAME="FLT_MIN_10_EXP"><CODE>FLT_MIN_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MIN_10_EXP</B> <I><integer rvalue <= -37></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X,</I> such that 10^<I>X</I>
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is a normalized, finite representable value of type <I>float.</I></P>
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<H2><A NAME="FLT_MIN_EXP"><CODE>FLT_MIN_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_MIN_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X,</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a normalized, finite representable value of type <I>float.</I></P>
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<H2><A NAME="FLT_RADIX"><CODE>FLT_RADIX</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_RADIX</B> <I><#if expression >= 2></I>
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</CODE></P>
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<P>The macro yields the radix of all floating-point representations.</P>
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<H2><A NAME="FLT_ROUNDS"><CODE>FLT_ROUNDS</CODE></A></H2>
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<P><CODE>
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#define <B>FLT_ROUNDS</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields a value that describes the current rounding
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mode for floating-point operations. Note that the target environment
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can change the rounding mode while the program executes. How it does
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so, however, is not specified. The values are:</P>
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<UL>
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<LI>-1 if the mode is indeterminate
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<LI>0 if rounding is toward zero
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<LI>1 if rounding is to nearest representable value
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<LI>2 if rounding is toward +infinity
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<LI>3 if rounding is toward -infinity
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</UL>
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<P>An implementation can define additional values for this macro.</P>
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<H2><A NAME="LDBL_DIG"><CODE>LDBL_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_DIG</B> <I><integer rvalue >= 10></I>
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</CODE></P>
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<P>The macro yields the precision in decimal digits for type <I>long
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double.</I></P>
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<H2><A NAME="LDBL_EPSILON"><CODE>LDBL_EPSILON</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_EPSILON</B> <I><long double rvalue <= 10^(-9)></I>
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</CODE></P>
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<P>The macro yields the smallest <I>X</I> of type <I>long double</I>
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such that 1.0 + <I>X</I> != 1.0.</P>
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<H2><A NAME="LDBL_MANT_DIG"><CODE>LDBL_MANT_DIG</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MANT_DIG</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the number of mantissa digits, base
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>,
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for type <I>long double.</I></P>
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<H2><A NAME="LDBL_MAX"><CODE>LDBL_MAX</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MAX</B> <I><long double rvalue >= 10^37></I>
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</CODE></P>
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<P>The macro yields the largest finite representable value of type
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<I>long double.</I></P>
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<H2><A NAME="LDBL_MAX_10_EXP"><CODE>LDBL_MAX_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MAX_10_EXP</B> <I><integer rvalue >= 37></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that
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10^<I>X</I> is a finite representable value of type <I>long double.</I></P>
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<H2><A NAME="LDBL_MAX_EXP"><CODE>LDBL_MAX_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MAX_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the maximum integer <I>X,</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a finite representable value of type <I>long double.</I></P>
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<H2><A NAME="LDBL_MIN"><CODE>LDBL_MIN</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MIN</B> <I><long double rvalue <= 10^(-37)></I>
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</CODE></P>
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<P>The macro yields the smallest normalized, finite representable
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value of type <I>long double.</I></P>
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<H2><A NAME="LDBL_MIN_10_EXP"><CODE>LDBL_MIN_10_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MIN_10_EXP</B> <I><integer rvalue <= -37></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X,</I> such that
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10^<I>X</I> is a normalized, finite representable value
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of type <I>long double.</I></P>
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<H2><A NAME="LDBL_MIN_EXP"><CODE>LDBL_MIN_EXP</CODE></A></H2>
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<P><CODE>
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#define <B>LDBL_MIN_EXP</B> <I><integer rvalue></I>
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</CODE></P>
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<P>The macro yields the minimum integer <I>X,</I> such that
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<A HREF="#FLT_RADIX"><CODE>FLT_RADIX</CODE></A>^(<I>X</I> - 1)
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is a normalized, finite representable value of type <I>long double.</I></P>
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<HR>
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<P>See also the
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<B><A HREF="index.html#Table of Contents" tppabs="http://ccs.ucsd.edu/c/index.html#Table of Contents">Table of Contents</A></B> and the
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<B><A HREF="_index.html" tppabs="http://ccs.ucsd.edu/c/_index.html">Index</A></B>.</P>
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<P><I>
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<A HREF="crit_pb.html" tppabs="http://ccs.ucsd.edu/c/crit_pb.html">Copyright</A> © 1989-1996
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by P.J. Plauger and Jim Brodie. All rights reserved.</I></P>
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</BODY></HTML>
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