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'\" t
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-1.0-or-later
.\"
.TH cproj 3 2025-05-17 "Linux man-pages (unreleased)"
.SH NAME
cproj, cprojf, cprojl \- project into Riemann Sphere
.SH LIBRARY
Math library
.RI ( libm ,\~ \-lm )
.SH SYNOPSIS
.nf
.B #include <complex.h>
.P
.BI "double complex cproj(double complex " z ");"
.BI "float complex cprojf(float complex " z ");"
.BI "long double complex cprojl(long double complex " z ");"
.fi
.SH DESCRIPTION
These functions project a point in the plane onto the surface of a
Riemann Sphere, the one-point compactification of the complex plane.
Each finite point
.I z
projects to
.I z
itself.
Every complex infinite value is projected to a single infinite value,
namely to positive infinity on the real axis.
.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 cproj (),
.BR cprojf (),
.BR cprojl ()
T} Thread safety MT-Safe
.TE
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
glibc 2.1.
C99, POSIX.1-2001.
.P
In glibc 2.11 and earlier, the implementation does something different
(a
.I stereographic
projection onto a Riemann Sphere).
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=10401
.SH SEE ALSO
.BR cabs (3),
.BR complex (7)
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