1.\" $OpenBSD: clog.3,v 1.2 2013/06/05 03:40:26 tedu Exp $ 2.\" 3.\" Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: June 5 2013 $ 18.Dt CLOG 3 19.Os 20.Sh NAME 21.Nm clog , 22.Nm clogf , 23.Nm clogl 24.Nd complex natural logarithm 25.Sh SYNOPSIS 26.In complex.h 27.Ft double complex 28.Fn clog "double complex z" 29.Ft float complex 30.Fn clogf "float complex z" 31.Ft long double complex 32.Fn clogl "long double complex z" 33.Sh DESCRIPTION 34The 35.Fn clog , 36.Fn clogf 37and 38.Fn clogl 39functions compute the complex logarithm to the base 40.Ms e 41(2.718...) of 42.Fa z . 43.Pp 44If 45.Fa z 46= x + iy, then 47.Bd -literal -offset indent 48clog(z) = log(sqrt(x^2 + y^2)) + i atan(y / x). 49.Ed 50.Sh RETURN VALUES 51The 52.Fn clog , 53.Fn clogf 54and 55.Fn clogl 56functions return the complex logarithm to the base 57.Ms e 58of 59.Fa z 60with imaginary part in the interval 61.Bq -Pi, Pi , 62and unbounded real part. 63.Sh SEE ALSO 64.Xr cexp 3 , 65.Xr cpow 3 66.Sh STANDARDS 67The 68.Fn clog , 69.Fn clogf 70and 71.Fn clogl 72functions conform to 73.St -isoC-99 . 74