xref: /freebsd/lib/msun/man/sqrt.3 (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
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32.\"     from: @(#)sqrt.3	6.4 (Berkeley) 5/6/91
33.\" $FreeBSD$
34.\"
35.Dd May 6, 1991
36.Dt SQRT 3
37.Os
38.Sh NAME
39.Nm cbrt ,
40.Nm cbrtf ,
41.Nm sqrt ,
42.Nm sqrtf
43.Nd cube root and square root functions
44.Sh SYNOPSIS
45.Fd #include <math.h>
46.Ft double
47.Fn cbrt "double x"
48.Ft float
49.Fn cbrtf "float x"
50.Ft double
51.Fn sqrt "double x"
52.Ft float
53.Fn sqrtf "float x"
54.Sh DESCRIPTION
55The
56.Fn cbrt
57and the
58.Fn cbrtf
59functions compute
60the cube root of
61.Ar x .
62.Pp
63The
64.Fn sqrt
65and the
66.Fn sqrtf
67functions compute the
68non-negative square root of x.
69.Sh RETURN VALUES
70The
71.Fn cbrt
72and the
73.Fn cbrtf
74functions return the requested cube root.
75The
76.Fn sqrt
77and the
78.Fn sqrtf
79functions return the requested square root
80unless an error occurs.
81On the
82.Tn VAX
83or
84.Tn Tahoe
85processor an attempt to take the
86.Fn sqrt
87of negative
88.Fa x
89causes an error; in this event,
90the global variable
91.Va errno
92is set to
93.Er EDOM
94and a reserved operand fault is generated.
95.Sh ERROR (due to Roundoff etc.)
96The
97.Fn cbrt
98function
99is accurate to within 0.7
100.Em ulps .
101.Pp
102The
103.Fn sqrt
104function on a
105.Tn VAX
106is accurate to within 0.501
107.Em ulps .
108Sqrt on a machine that conforms to
109.Tn IEEE
110754 is correctly rounded
111in accordance with the rounding mode in force; the error is less than
112half an
113.Em ulp
114in the default mode (round\-to\-nearest).
115An
116.Em ulp
117is one
118.Em U Ns nit
119in the
120.Em L Ns ast
121.Em P Ns lace
122carried.
123.Sh SEE ALSO
124.Xr math 3
125.Sh STANDARDS
126The
127.Fn sqrt
128function conforms to
129.St -isoC .
130.Sh HISTORY
131The
132.Fn cbrt
133function appeared in
134.Bx 4.3 .
135