uniroot(stats)
uniroot()所属R语言包：stats
One Dimensional Root (Zero) Finding
一维根（零）侦测
译者：生物统计家园网 机器人LoveR
描述----------Description----------
The function uniroot searches the interval from lower to upper for a root (i.e., zero) of the function f with respect to its first argument.
功能uniroot搜索区间的功能lower根（即零），其第一个参数的upperf。
用法----------Usage----------
uniroot(f, interval, ...,
lower = min(interval), upper = max(interval),
f.lower = f(lower, ...), f.upper = f(upper, ...),
tol = .Machine$double.eps^0.25, maxiter = 1000)
参数----------Arguments----------
参数：f
the function for which the root is sought.
这根要求的功能。
参数：interval
a vector containing the end-points of the interval to be searched for the root.
一个向量，包含根搜查间隔终点。
参数：...
additional named or unnamed arguments to be passed to f
额外的有名或无名的论据要传递f的
参数：lower, upper
the lower and upper end points of the interval to be searched.
要搜索的区间的下限和上限的终点。
参数：f.lower, f.upper
the same as f(upper) and f(lower), respectively. Passing these values from the caller where they are often known is more economical as soon as f() contains non-trivial computations.
f(upper)和f(lower)，分别相同。从来电，他们通常被称为传递这些值是更为经济尽快f()包含了不平凡的计算的。
参数：tol
the desired accuracy (convergence tolerance).
所需的精度（收敛宽容）。
参数：maxiter
the maximum number of iterations.
最大迭代次数。
Details
详情----------Details----------
Note that arguments after ... must be matched exactly.
请注意，后...参数必须完全匹配。
Either interval or both lower and upper must be specified: the upper endpoint must be strictly larger than the lower endpoint. The function values at the endpoints must be of opposite signs (or zero).
要么interval都lower和upper必须指定：上端点必须严格比下端点较大。在端点的函数值必须是相反的迹象（或零）。
The function uses Fortran subroutine ""zeroin"" (from Netlib) based on algorithms given in the reference below. They assume a continuous function (which then is known to have at least one root in the interval).
该功能使用Fortran子程序"zeroin"（NETLIB）的基础上参考下面给出的算法。他们假设一个连续函数（然后已知至少有一个根在区间）。
Convergence is declared either if f(x) == 0 or the change in x for one step of the algorithm is less than tol (plus an allowance for representation error in x).
收敛声明或者如果f(x) == 0或改变x算法的一个步骤是小于tol（加上x错误表示的免税额）。
If the algorithm does not converge in maxiter steps, a warning is printed and the current approximation is returned.
如果算法不收敛maxiter步骤，一个警告被打印和返回的电流近似。
f will be called as f(<VAR>x</VAR>, ...) for a numeric value of <VAR>x</VAR>.
ff(<VAR>x</VAR>, ...)的<VAR>的数值将被称为X </变更>。
值----------Value----------
A list with four components: root and f.root give the location of the root and the value of the function evaluated at that point. iter and estim.prec give the number of iterations used and an approximate estimated precision for root. (If the root occurs at one of the endpoints, the estimated precision is NA.)
四部分组成的一个列表：root和f.root根的位置和价值评估的功能，在这一点上。 iter和estim.prec使用迭代和一个近似的估计精度root。 （如果根发生在一个端点，估计精度是NA。）
源----------Source----------
Based on "zeroin.c" in http://www.netlib.org/c/brent.shar.
基于zeroin.chttp://www.netlib.org/c/brent.shar。
参考文献----------References----------
Algorithms for Minimization without Derivatives. Englewood Cliffs, NJ: Prentice-Hall.
参见----------See Also----------
polyroot for all complex roots of a polynomial; optimize, nlm.
polyroot多项式所有复杂的根源; optimize，nlm。
举例----------Examples----------
require(utils) # for str[为STR]
## some platforms hit zero exactly on the first step:[＃某些平台上准确击中第一步零：]
## if so the estimated precision is 2/3.[＃如果估计的精度是2/3。]
f <- function (x,a) x - a
str(xmin <- uniroot(f, c(0, 1), tol = 0.0001, a = 1/3))
## handheld calculator example: fixpoint of cos(.):[＃手持计算器的例子：COS的不动点（。）：]
rc <- uniroot(function(x) cos(x) - x, lower=-pi, upper=pi, tol = 1e-9)
rc$root
str(uniroot(function(x) x*(x^2-1) + .5, lower = -2, upper = 2,
tol = 0.0001))
str(uniroot(function(x) x*(x^2-1) + .5, lower = -2, upper = 2,
tol = 1e-10 ))
## Find the smallest value x for which exp(x) > 0 (numerically):[＃查找最小的x值EXP（X）> 0（数字）：]
r <- uniroot(function(x) 1e80*exp(x)-1e-300, c(-1000,0), tol = 1e-15)
str(r, digits.d = 15) ##> around -745, depending on the platform.[＃> -745左右，取决于平台。]
exp(r$root) # = 0, but not for r$root * 0.999...[= 0，但并非为R $根* 0.999 ...]
minexp <- r$root * (1 - 10*.Machine$double.eps)
exp(minexp) # typically denormalized[通常非规格化]
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-2-16 22:06:37
