mirror of https://github.com/mkerrisk/man-pages
62 lines
1.7 KiB
Groff
62 lines
1.7 KiB
Groff
.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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.\" Distributed under GPL
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.\" 2002-07-27 Walter Harms
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.\" this was done with the help of the glibc manual
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.\"
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.TH ISGREATER 3 2002-07-27 "" "Linux Programmer's Manual"
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.SH NAME
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isgreater, isgreaterequal, isless, islessgreater, isunordered \- macros
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to test a relation
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.SH SYNOPSIS
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.nf
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.B #include <math.h>
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.sp
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.BI "int isgreater(x,y);"
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.sp
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.BI "int isgreaterequal(x,y);"
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.sp
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.BI "int isless(x,y);"
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.sp
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.BI "int islessequal(x,y);"
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.sp
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.BI "int islessgreater(x,y);"
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.sp
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.BI "int isunordered(x,y);"
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.fi
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.sp
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Compile with \-std=c99; link with \-lm.
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.SH DESCRIPTION
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The normal relation operations (like less) will fail if one of the
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operands is NaN. This will cause an exception. To avoid this, C99 defines
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these macros. The macros are guaranteed to evaluate their operands only once.
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The operand can be of any real floating-point type.
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.TP
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isgreater()
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determines (x) > (y) without an exception if x or y is NaN.
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.TP
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isgreaterequal()
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determines (x) >= (y) without an exception if x or y is NaN.
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.TP
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isless()
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determines (x) < (y) without an exception if x or y is NaN.
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.TP
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islessequal()
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determines (x) <= (y) without an exception if x or y is NaN.
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.TP
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islessgreater()
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determines (x) < (y) || (x) > (y) without an exception if x or y is NaN.
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This macro is not equivalent to x != y because that expression is
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true if x or y is NaN.
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.TP
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isunordered()
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is true if x or y is NaN and false otherwise.
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.SH NOTE
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Not all hardware supports these functions, and where it doesn't, they
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will be emulated by macros. This will give you a performance penalty.
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Don't use these functions if NaN is of no concern for you.
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.SH "CONFORMING TO"
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C99
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.SH "SEE ALSO"
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.BR fpclassify (3)
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.BR isnan (3)
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