NAME
cbrt, sqrt
— cube root and square root
functions
SYNOPSIS
#include
<math.h>
double
cbrt(double
x);
double
sqrt(double
x);
DESCRIPTION
Thecbrt()
function computes the cube root of x.
The
sqrt()
computes the non-negative square root of x.
RETURN VALUES
The cbrt() function returns the requested
cube root. The sqrt() function returns the requested
square root unless an error occurs. On the VAX or Tahoe processor an attempt
to take the sqrt() of negative
x causes an error; in this event, the global variable
errno is set to EDOM and a
reserved operand fault is generated.
ERROR (due to Roundoff etc.)
The cbrt() function is accurate to within
0.7 ulps.
The
sqrt()
function on a VAX is accurate to within 0.501 ulps. Sqrt
on a machine that conforms to IEEE 754 is correctly rounded in accordance
with the rounding mode in force; the error is less than half an
ulp in the default mode (round-to-nearest). An
ulp is one
Unit in the
Last
Place
carried.
SEE ALSO
STANDARDS
The sqrt function conforms to
ANSI X3.159-1989
(“ANSI C89”).
HISTORY
The cbrt function appeared in
4.3BSD.