cbrt, cbrtf, sqrt, sqrtf -- cube root and square root functions
Math Library (libm, -lm)
The cbrt() and the cbrtf() functions compute the cube root of x.
The sqrt() and the sqrtf() functions compute the non-negative square root
The cbrt() and the cbrtf() functions return the requested cube root. The
sqrt() and the sqrtf() functions return 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.) [Toc] [Back]
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
The sqrt() function conforms to ISO/IEC 9899:1990 (``ISO C89'').
The cbrt() function appeared in 4.3BSD.
FreeBSD 5.2.1 May 6, 1991 FreeBSD 5.2.1 [ Back ]