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diff --git a/man/man3/fmod.3 b/man/man3/fmod.3 new file mode 100644 index 000000000..d6c76c7a3 --- /dev/null +++ b/man/man3/fmod.3 @@ -0,0 +1,183 @@ +'\" t +.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) +.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" 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 2002-07-27 by Walter Harms +.\" (walter.harms@informatik.uni-oldenburg.de) +.\" +.TH fmod 3 (date) "Linux man-pages (unreleased)" +.SH NAME +fmod, fmodf, fmodl \- floating-point remainder function +.SH LIBRARY +Math library +.RI ( libm ", " \-lm ) +.SH SYNOPSIS +.nf +.B #include <math.h> +.P +.BI "double fmod(double " x ", double " y ); +.BI "float fmodf(float " x ", float " y ); +.BI "long double fmodl(long double " x ", long double " y ); +.fi +.P +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR fmodf (), +.BR fmodl (): +.nf + _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L + || /* Since glibc 2.19: */ _DEFAULT_SOURCE + || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE +.fi +.SH DESCRIPTION +These functions compute the floating-point remainder of dividing +.I x +by +.IR y . +The return value is +.I x +\- +.I n +* +.IR y , +where +.I n +is the quotient of +.I x +/ +.IR y , +rounded toward zero to an integer. +.P +To obtain the modulus, more specifically, the Least Positive Residue, +you will need to adjust the result from fmod like so: +.P +.in +4n +.nf +z = fmod(x, y); +if (z < 0) + z += y; +.fi +.in +.P +An alternate way to express this is with +.IR "fmod(fmod(x, y) + y, y)" , +but the second +.BR fmod () +usually costs way more than the one branch. +.SH RETURN VALUE +On success, these +functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP, +for some integer +.IR n , +such that the returned value has the same sign as +.I x +and a magnitude less than the magnitude of +.IR y . +.P +If +.I x +or +.I y +is a NaN, a NaN is returned. +.P +If +.I x +is an infinity, +a domain error occurs, and +a NaN is returned. +.P +If +.I y +is zero, +a domain error occurs, and +a NaN is returned. +.P +If +.I x +is +0 (\-0), and +.I y +is not zero, +0 (\-0) is returned. +.SH ERRORS +See +.BR math_error (7) +for information on how to determine whether an error has occurred +when calling these functions. +.P +The following errors can occur: +.TP +Domain error: \fIx\fP is an infinity +.I errno +is set to +.B EDOM +(but see BUGS). +An invalid floating-point exception +.RB ( FE_INVALID ) +is raised. +.TP +Domain error: \fIy\fP is zero +.I errno +is set to +.BR EDOM . +An invalid floating-point exception +.RB ( FE_INVALID ) +is raised. +.\" POSIX.1 documents an optional underflow error, but AFAICT it doesn't +.\" (can't?) occur -- mtk, Jul 2008 +.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 fmod (), +.BR fmodf (), +.BR fmodl () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +C99, POSIX.1-2001. +.P +The variant returning +.I double +also conforms to +SVr4, 4.3BSD, C89. +.SH BUGS +Before glibc 2.10, the glibc implementation did not set +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6784 +.I errno +to +.B EDOM +when a domain error occurred for an infinite +.IR x . +.SH EXAMPLES +The call +.I fmod(372, 360) +returns 348. +.P +The call +.I fmod(-372, 360) +returns -12. +.P +The call +.I fmod(-372, -360) +also returns -12. +.SH SEE ALSO +.BR remainder (3) |