SQRT(3) BSD Programmer's Manual SQRT(3)
cbrt, sqrt - cube root and square root functions
The cbrt() function computes the cube root of x.
The sqrt() computes the non-negative square root of x.
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 er-
ror; in this event, the global variable errno is set to EDOM and a re-
served 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 de-
fault mode (round-to-nearest). An ulp is one Unit in the Last Place car-
The sqrt function conforms to ANSI C X3.159-1989 (``ANSI C '').
The cbrt function appeared in 4.3BSD.
4.4BSD June 4, 1993 1