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diff --git a/man-pages-posix-2013/man3p/fabs.3p b/man-pages-posix-2013/man3p/fabs.3p new file mode 100644 index 0000000..e3ebcb4 --- /dev/null +++ b/man-pages-posix-2013/man3p/fabs.3p @@ -0,0 +1,119 @@ +'\" et +.TH FABS "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. + +.SH NAME +fabs, +fabsf, +fabsl +\(em absolute value function +.SH SYNOPSIS +.LP +.nf +#include <math.h> +.P +double fabs(double \fIx\fP); +float fabsf(float \fIx\fP); +long double fabsl(long double \fIx\fP); +.fi +.SH DESCRIPTION +The functionality described on this reference page is aligned with the +ISO\ C standard. Any conflict between the requirements described here and the +ISO\ C standard is unintentional. This volume of POSIX.1\(hy2008 defers to the ISO\ C standard. +.P +These functions shall compute the absolute value of their argument +.IR x ,|\c +.IR x |. +.SH "RETURN VALUE" +Upon successful completion, these functions shall return the absolute +value of +.IR x . +.P +If +.IR x +is NaN, a NaN shall be returned. +.P +If +.IR x +is \(+-0, +0 shall be returned. +.P +If +.IR x +is \(+-Inf, +Inf shall be returned. +.SH ERRORS +No errors are defined. +.LP +.IR "The following sections are informative." +.SH EXAMPLES +.SS "Computing the 1-Norm of a Floating-Point Vector" +.P +This example shows the use of +\fIfabs\fR() +to compute the 1-norm of a vector defined as follows: +.sp +.RS 4 +.nf +\fB +norm1(v) = |v[0]| + |v[1]| + ... + |v[n\(mi1]| +.fi \fR +.P +.RE +.P +where |\fIx\fR| denotes the absolute value of \fIx\fR, \fIn\fR denotes +the vector's dimension \fIv\fR[\fIi\fR] denotes the +.IR i -th +component of \fIv\fR (0\(<=\fIi\fR<\fIn\fR). +.sp +.RS 4 +.nf +\fB +#include <math.h> +.P +double +norm1(const double v[], const int n) +{ + int i; + double n1_v; /* 1-norm of v */ +.P + n1_v = 0; + for (i=0; i<n; i++) { + n1_v += fabs (v[i]); + } +.P + return n1_v; +} +.fi \fR +.P +.RE +.SH "APPLICATION USAGE" +None. +.SH RATIONALE +None. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIisnan\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "\fB<math.h>\fP" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, Copyright (C) 2013 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.unix.org/online.html . + +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |