1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)sqrt.3 8.1 (Berkeley) 06/04/93 7.\" 8.Dd 9.Dt SQRT 3 10.Os 11.Sh NAME 12.Nm cbrt , 13.Nm sqrt 14.Nd cube root and square root functions 15.Sh SYNOPSIS 16.Fd #include <math.h> 17.Ft double 18.Fn cbrt "double x" 19.Ft double 20.Fn sqrt "double x" 21.Sh DESCRIPTION 22The 23.Fn cbrt 24function computes 25the cube root of 26.Ar x . 27.Pp 28The 29.Fn sqrt 30computes the 31non-negative square root of x. 32.Sh RETURN VALUES 33The 34.Fn cbrt 35function returns the requested cube root. 36The 37.Fn sqrt 38function returns the requested square root 39unless an error occurs. 40On the 41.Tn VAX 42or 43.Tn Tahoe 44processor an attempt to take the 45.Fn sqrt 46of negative 47.Fa x 48causes an error; in this event, 49the global variable 50.Va errno 51is set to 52.Dv EDOM 53and a reserved operand fault is generated. 54.Sh ERROR (due to Roundoff etc.) 55The 56.Fn cbrt 57function 58is accurate to within 0.7 59.Em ulps . 60.Pp 61The 62.Fn sqrt 63function on a 64.Tn VAX 65is accurate to within 0.501 66.Em ulps . 67Sqrt on a machine that conforms to 68.Tn IEEE 69754 is correctly rounded 70in accordance with the rounding mode in force; the error is less than 71half an 72.Em ulp 73in the default mode (round\-to\-nearest). 74An 75.Em ulp 76is one 77.Em U Ns nit 78in the 79.Em L Ns ast 80.Em P Ns lace 81carried. 82.Sh SEE ALSO 83.Xr math 3 , 84.Xr infnan 3 85.Sh STANDARDS 86The 87.Nm sqrt 88function conforms to 89.St -ansiC . 90.Sh HISTORY 91The 92.Nm cbrt 93function appeared in 94.Bx 4.3 . 95