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from: @(#)sqrt.3 6.4 (Berkeley) 5/6/91
$Id: sqrt.3,v 1.2 1995/03/01 05:06:41 jkh Exp $
.Dd May 6, 1991 .Dt SQRT 3 .Os .Sh NAME .Nm cbrt , .Nm cbrtf , .Nm sqrt , .Nm sqrtf .Nd cube root and square root functions .Sh SYNOPSIS .Fd #include <math.h> .Ft double .Fn cbrt "double x" .Ft float .Fn cbrtf "float x" .Ft double .Fn sqrt "double x" .Ft float .Fn sqrtf "float x" .Sh DESCRIPTION The .Fn cbrt and the .Fn cbrtf functions compute the cube root of .Ar x .
p The .Fn sqrt and the .Fn sqrtf functions compute the non-negative square root of x. .Sh RETURN VALUES The .Fn cbrt and the .Fn cbrtf functions return the requested cube root. The .Fn sqrt and the .Fn sqrtf functions return the requested square root unless an error occurs. On the .Tn VAX or .Tn Tahoe processor an attempt to take the .Fn sqrt of negative .Fa x causes an error; in this event, the global variable .Va errno is set to .Dv EDOM and a reserved operand fault is generated. .Sh ERROR (due to Roundoff etc.) The .Fn cbrt function is accurate to within 0.7 .Em ulps .
p The .Fn sqrt function on a .Tn VAX is accurate to within 0.501 .Em ulps . Sqrt on a machine that conforms to .Tn IEEE 754 is correctly rounded in accordance with the rounding mode in force; the error is less than half an .Em ulp in the default mode (round-to-nearest). An .Em ulp is one .Em U Ns nit in the .Em L Ns ast .Em P Ns lace carried. .Sh SEE ALSO .Xr math 3 .Sh STANDARDS The .Nm sqrt function conforms to .St -ansiC . .Sh HISTORY The .Nm cbrt function appeared in x 4.3 .