76 lines
2.8 KiB
C
76 lines
2.8 KiB
C
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/* isgreater.c: This file contains no source code, but rather only the
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* man-page comments. All of the documented "functions" are actually macros
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* defined in math.h (q.v.). */
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/*
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FUNCTION
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<<isgreater>>, <<isgreaterequal>>, <<isless>>, <<islessequal>>, <<islessgreater>>, and <<isunordered>>--comparison macros
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INDEX
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isgreater
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INDEX
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isgreaterequal
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INDEX
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isless
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INDEX
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islessequal
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INDEX
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islessgreater
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INDEX
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isunordered
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ANSI_SYNOPSIS
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#include <math.h>
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int isgreater(real-floating <[x]>, real-floating <[y]>);
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int isgreaterequal(real-floating <[x]>, real-floating <[y]>);
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int isless(real-floating <[x]>, real-floating <[y]>);
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int islessequal(real-floating <[x]>, real-floating <[y]>);
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int islessgreater(real-floating <[x]>, real-floating <[y]>);
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int isunordered(real-floating <[x]>, real-floating <[y]>);
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DESCRIPTION
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<<isgreater>>, <<isgreaterequal>>, <<isless>>, <<islessequal>>,
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<<islessgreater>>, and <<isunordered>> are macros defined for use in
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comparing floating-point numbers without raising any floating-point
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exceptions.
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The relational operators (i.e. <, >, <=, and >=) support the usual mathematical
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relationships between numeric values. For any ordered pair of numeric
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values exactly one of the relationships--less, greater, and equal--is
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true. Relational operators may raise the "invalid" floating-point
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exception when argument values are NaNs. For a NaN and a numeric value, or
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for two NaNs, just the unordered relationship is true (i.e., if one or both
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of the arguments a NaN, the relationship is called unordered). The specified
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macros are quiet (non floating-point exception raising) versions of the
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relational operators, and other comparison macros that facilitate writing
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efficient code that accounts for NaNs without suffering the "invalid"
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floating-point exception. In the synopses shown, "real-floating" indicates
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that the argument is an expression of real floating type.
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Please note that saying that the macros do not raise floating-point
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exceptions, it is referring to the function that they are performing. It
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is certainly possible to give them an expression which causes an exception.
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For example:
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o+
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o NaN < 1.0
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causes an "invalid" exception,
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o isless(NaN, 1.0)
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does not, and
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o isless(NaN*0., 1.0)
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causes an exception due to the "NaN*0.", but not from the
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resultant reduced comparison of isless(NaN, 1.0).
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o-
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RETURNS
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@comment Formatting note: "$@" forces a new line
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No floating-point exceptions are raised for any of the macros.@*
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The <<isgreater>> macro returns the value of (x) > (y).@*
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The <<isgreaterequal>> macro returns the value of (x) >= (y).@*
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The <<isless>> macro returns the value of (x) < (y).@*
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The <<islessequal>> macro returns the value of (x) <= (y).@*
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The <<islessgreater>> macro returns the value of (x) < (y) || (x) > (y).@*
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The <<isunordered>> macro returns 1 if either of its arguments is NaN and 0 otherwise.
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PORTABILITY
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C99, POSIX.
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*/
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