sqrt.3m

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3M 代码 · 共 49 行

.TH sqrt 3m RISC
.ds up \fIulp\fR
.ds nn \fINaN\fR
.SH Name
cbrt, sqrt \- cube root, square root
.SH Syntax
.nf
.B #include <math.h>
.PP
.B double cbrt(\fIx\fP)
.B double \fIx\fP;
.PP
.B double sqrt(\fIx\fP)
.B double \fIx\fP;
.PP
.B float fsqrt(float \fIx\fP)
.B float \fIx\fP;
.fi
.SH Description
The 
.PN cbrt
function returns the cube root of \fIx\fP.
.PP
The 
.PN sqrt 
and
.PN fsqrt
functions return the square root of \fIx\fP for double and float
data types respectively.
.SS "Error Due to Roundoff and Other Reasons"
The 
.PN cbrt
function is accurate to within 0.7 \*(ups.
.PP
The 
.PN sqrt
function on this machine conforms to IEEE 754 and is correctly rounded
in accordance with the rounding mode in force; the error is less than
half an \*(up in the default mode (round\-to\-nearest).
An \*(up is one \fIU\fRnit in the \fIL\fRast \fIP\fRlace carried.
.SH Diagnostics
The 
.PN sqrt
function returns the default quiet \*(nn when 
.I x\^
is negative indicating the invalid operation.
.SH See Also
math(3m)