isgreater, isgreaterequal, isless, islessequal, islessgreater, isunordered - floating-point relational tests without exception for NaN
#include <math.h> int isgreater(x, y); int isgreaterequal(x, y); int isless(x, y); int islessequal(x, y); int islessgreater(x, y); int isunordered(x, y); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
The normal relational operations (like <, "less than") will fail if one of the operands is NaN. This will cause an exception. To avoid this, C99 defines the macros listed below. 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 not be promoted to real-floating types). isgreater() determines (x) > (y) without an exception if x or y is NaN. isgreaterequal() determines (x) >= (y) without an exception if x or y is NaN. isless() determines (x) < (y) without an exception if x or y is NaN. islessequal() determines (x) <= (y) without an exception if x or y is NaN. islessgreater() determines (x) < (y) || (x) > (y) without an exception if x or y is NaN. This macro is not equivalent to x != y because that expression is true if x or y is NaN. isunordered() determines whether its arguments are unordered, that is, whether at least one of the arguments is a NaN.
The macros other than isunordered() return the result of the relational comparison; these macros return 0 if either argument is a NaN. isunordered() returns 1 if x or y is NaN and 0 otherwise.
No errors occur.
For an explanation of the terms used in this section, see attributes(7). ┌───────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├───────────────────────────────┼───────────────┼─────────┤ │isgreater(), isgreaterequal(), │ Thread safety │ MT-Safe │ │isless(), islessequal(), │ │ │ │islessgreater(), isunordered() │ │ │ └───────────────────────────────┴───────────────┴─────────┘
POSIX.1-2001, POSIX.1-2008, C99.
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.
This page is part of release 4.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. 2016-03-15 ISGREATER(3)
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.