'\" t .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk .\" .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .\" References consulted: .\" Linux libc source code .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) .\" 386BSD man pages .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) .\" Modified 1995-08-14 by Arnt Gulbrandsen .\" Modified 2002-07-27 by Walter Harms .\" (walter.harms@informatik.uni-oldenburg.de) .\" .TH exp2 3 2024-05-02 "Linux man-pages 6.9.1" .SH NAME exp2, exp2f, exp2l \- base-2 exponential function .SH LIBRARY Math library .RI ( libm ", " \-lm ) .SH SYNOPSIS .nf .B #include .P .BI "double exp2(double " x ); .BI "float exp2f(float " x ); .BI "long double exp2l(long double " x ); .fi .P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .P .BR exp2 (), .BR exp2f (), .BR exp2l (): .nf _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L .fi .SH DESCRIPTION These functions return the value of 2 raised to the power of .IR x . .SH RETURN VALUE On success, these functions return the base-2 exponential value of .IR x . .P For various special cases, including the handling of infinity and NaN, as well as overflows and underflows, see .BR exp (3). .SH ERRORS See .BR math_error (7) for information on how to determine whether an error has occurred when calling these functions. .P For a discussion of the errors that can occur for these functions, see .BR exp (3). .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ .na .nh .BR exp2 (), .BR exp2f (), .BR exp2l () T} Thread safety MT-Safe .TE .SH STANDARDS C11, POSIX.1-2008. .SH HISTORY glibc 2.1. C99, POSIX.1-2001. .P The variant returning .I double also conforms to SVr4, 4.3BSD. .SH SEE ALSO .BR cbrt (3), .BR cexp2 (3), .BR exp (3), .BR exp10 (3), .BR sqrt (3)