| .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) |
| .\" |
| .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE) |
| .\" Distributed under GPL |
| .\" %%%LICENSE_END |
| .\" |
| .\" 2002-07-27 Walter Harms |
| .\" this was done with the help of the glibc manual |
| .\" |
| .TH ISGREATER 3 2021-03-22 "" "Linux Programmer's Manual" |
| .SH NAME |
| isgreater, isgreaterequal, isless, islessequal, islessgreater, |
| isunordered \- floating-point relational tests without exception for NaN |
| .SH SYNOPSIS |
| .nf |
| .B #include <math.h> |
| .PP |
| .BI "int isgreater(" x ", " y ); |
| .BI "int isgreaterequal(" x ", " y ); |
| .BI "int isless(" x ", " y ); |
| .BI "int islessequal(" x ", " y ); |
| .BI "int islessgreater(" x ", " y ); |
| .BI "int isunordered(" x ", " y ); |
| .fi |
| .PP |
| Link with \fI\-lm\fP. |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .nf |
| All functions described here: |
| _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L |
| .fi |
| .SH DESCRIPTION |
| The normal relational operations (like |
| .BR < , |
| "less than") |
| fail if one of the operands is NaN. |
| This will cause an exception. |
| To avoid this, C99 defines the macros listed below. |
| .PP |
| These macros are guaranteed to evaluate their arguments only once. |
| The arguments must be of real floating-point type (note: do not pass |
| integer values as arguments to these macros, since the arguments will |
| .I not |
| be promoted to real-floating types). |
| .TP |
| .BR isgreater () |
| determines \fI(x)\ >\ (y)\fP without an exception |
| if |
| .IR x |
| or |
| .I y |
| is NaN. |
| .TP |
| .BR isgreaterequal () |
| determines \fI(x)\ >=\ (y)\fP without an exception |
| if |
| .IR x |
| or |
| .I y |
| is NaN. |
| .TP |
| .BR isless () |
| determines \fI(x)\ <\ (y)\fP without an exception |
| if |
| .IR x |
| or |
| .I y |
| is NaN. |
| .TP |
| .BR islessequal () |
| determines \fI(x)\ <=\ (y)\fP without an exception |
| if |
| .IR x |
| or |
| .I y |
| is NaN. |
| .TP |
| .BR islessgreater () |
| determines \fI(x)\ < (y) || (x) >\ (y)\fP |
| without an exception if |
| .IR x |
| or |
| .I y |
| is NaN. |
| This macro is not equivalent to \fIx\ !=\ y\fP because that expression is |
| true if |
| .IR x |
| or |
| .I y |
| is NaN. |
| .TP |
| .BR isunordered () |
| determines whether its arguments are unordered, that is, whether |
| at least one of the arguments is a NaN. |
| .SH RETURN VALUE |
| The macros other than |
| .BR isunordered () |
| return the result of the relational comparison; |
| these macros return 0 if either argument is a NaN. |
| .PP |
| .BR isunordered () |
| returns 1 if |
| .IR x |
| or |
| .I y |
| is NaN and 0 otherwise. |
| .SH ERRORS |
| No errors occur. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR isgreater (), |
| .BR isgreaterequal (), |
| .BR isless (), |
| .BR islessequal (), |
| .BR islessgreater (), |
| .BR isunordered () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, C99. |
| .SH NOTES |
| Not all hardware supports these functions, |
| and where hardware support isn't provided, they will be emulated by macros. |
| This will result in a performance penalty. |
| Don't use these functions if NaN is of no concern for you. |
| .SH SEE ALSO |
| .BR fpclassify (3), |
| .BR isnan (3) |
