xref: /freebsd/lib/msun/man/clog.3 (revision 6be3386466ab79a84b48429ae66244f21526d3df)
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25.\" $FreeBSD$
26.\"
27.Dd June 6, 2018
28.Dt CLOG 3
29.Os
30.Sh NAME
31.Nm clog ,
32.Nm clogf ,
33and
34.Nm clogl
35.Nd complex natural logarithm functions
36.Sh LIBRARY
37.Lb libm
38.Sh SYNOPSIS
39.In complex.h
40.Ft double complex
41.Fn clog "double complex z"
42.Ft float complex
43.Fn clogf "float complex z"
44.Ft long double complex
45.Fn clogl "long double complex z"
46.Sh DESCRIPTION
47The
48.Fn clog ,
49.Fn clogf ,
50and
51.Fn clogl
52functions compute the complex natural logarithm of
53.Fa z .
54with a branch cut along the negative real axis .
55.Sh RETURN VALUES
56The
57.Fn clog
58function returns the complex natural logarithm value, in the
59range of a strip mathematically unbounded along the real axis and in
60the interval [-I* \*(Pi , +I* \*(Pi ] along the imaginary axis.
61The function satisfies the relationship:
62.Fo clog
63.Fn conj "z" Fc
64=
65.Fo conj
66.Fn clog "z" Fc .
67.Pp
68.\" Table is formatted for an 80-column xterm.
69.Bl -column ".Sy +\*(If + I*\*(Na" ".Sy Return value" ".Sy Divide-by-zero exception"
70.It Sy Argument          Ta Sy Return value Ta Sy Comment
71.It -0 + I*0             Ta -\*(If + I*\*(Pi    Ta Divide-by-zero exception
72.It                      Ta                     Ta raised
73.It +0 + I*0             Ta -\*(If + I*0        Ta Divide by zero exception
74.It                      Ta                     Ta raised
75.It x + I*\*(If          Ta +\*(If + I*\*(Pi/2  Ta For finite x
76.It x + I*\*(Na          Ta  \*(Na + I*\*(Na    Ta Optionally raises invalid
77.It                      Ta                     Ta floating-point exception
78.It                      Ta                     Ta for finite x
79.It -\*(If + I*y         Ta +\*(If + I*\*(Pi    Ta For finite positive-signed y
80.It +\*(If + I*y         Ta +\*(If + I*0        Ta For finite positive-signed y
81.It -\*(If + I*\*(If     Ta +\*(If + I*3\*(Pi/4
82.It +\*(If + I*\*(If     Ta +\*(If + I*\*(Pi/4
83.It \*(Pm\*(If + I*\*(Na Ta +\*(If + I*\*(Na
84.It \*(Na + I*y          Ta \*(Na + I*\*(Na    Ta Optionally raises invalid
85.It                      Ta                    Ta floating-point exception
86.It                      Ta                    Ta for finite y
87.It \*(Na + I*\*(If      Ta +\*(If + I*\*(Na
88.It \*(Na + I*\*(Na      Ta \*(Na + I*\*(Na
89.El
90.Sh SEE ALSO
91.Xr complex 3 ,
92.Xr log 3 ,
93.Xr math 3
94.Sh STANDARDS
95The
96.Fn clog ,
97.Fn cexpf ,
98and
99.Fn clogl
100functions conform to
101.St -isoC-99 .
102