Description Usage Arguments Details Value Author(s) References See Also Examples
Bracket the zeros (roots) of a univariate function
1 2 3 4 5 |
fun |
a univariate function; it will be called as |
interval |
a numeric vector, containing the end-points of the interval to be searched |
... |
further arguments passed to |
lower |
lower end-point. Ignored if |
upper |
upper end-point. Ignored if |
n |
the number of function evaluations. Must be at least 2 (in which
case |
method |
can be |
mc.control |
a list containing settings that will be passed to |
cl |
default is |
bracketing
evaluates fun
at equal-spaced values of x
between (and including) lower
and upper
. If the sign of
fun
changes between two consecutive x
-values,
bracketing
reports these two x
-values as containing (‘bracketing’)
a root. There is no guarantee that there is only one root
within a reported interval. bracketing
will not narrow the chosen intervals.
The argument method
determines how fun
is
evaluated. Default is loop
. If method == "vectorised"
,
fun
must be written such that it can be evaluated for a vector
x
(see Examples). If method
is multicore
,
function mclapply
from package parallel is used. Further
settings for mclapply
can be passed through the list
mc.control
. If multicore
is chosen but the functionality
is not available (eg, currently on Windows), then method
will
be set to loop
and a warning is issued. If method
is
snow
, function clusterApply
from package snow is
used. In this case, the argument cl
must either be a cluster
object (see the documentation of clusterApply
) or an
integer. If an integer, a cluster will be set up via
makeCluster(c(rep("localhost", cl)), type = "SOCK")
, and
stopCluster
is called when the function is exited. If
snow
is chosen but the package is not available or cl
is
not specified, then method
will be set to loop
and a
warning is issued. In case that cl
is a cluster object,
stopCluster
will not be called automatically.
a numeric matrix with two columns. Each row contains one interval that contains at least one root. If no roots were found, the matrix has zero rows.
Enrico Schumann
Gilli, M., Maringer, D. and Schumann, E. (2011) Numerical Methods and Optimization in Finance. Elsevier. http://www.elsevierdirect.com/product.jsp?isbn=9780123756626
Schumann, E. (2013) The NMOF Manual. http://enricoschumann.net/NMOF.htm
uniroot
(in package stats)
1 2 3 4 5 6 | ## Gilli/Maringer/Schumann (2011), p. 290
testFun <- function(x)
cos(1/x^2)
bracketing(testFun, interval = c(0.3, 0.9), n = 26L)
bracketing(testFun, interval = c(0.3, 0.9), n = 26L, method = "vectorised")
|
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