Rmpfr (version 0.9-5)

sapplyMpfr: Apply a Function over a "mpfr" Vector

Description

Users may be disappointed to note that sapply() or vapply() typically do not work with "mpfr" numbers.

This is a simple (but strong) approach to work around the problem, based on lapply().

Usage

sapplyMpfr(X, FUN, ..., drop_1_ = TRUE)

Value

an "mpfr" vector, typically of the same length as X.

Arguments

X

a vector, possibly of class "mpfr".

FUN

a function returning an "mpfr" vector or even an "mpfrArray". May also be a function returning a numeric vector or array for numeric X, and which returns "mpfr(Array)" for an X argument inheriting from "mpfr".

...

further arguments passed to lapply, typically further arguments to FUN.

drop_1_

logical (with unusual name on purpose!) indicating if 1-column matrices ("mpfrMatrix") should be “dropped” to vectors ("mpfr"), the same as in base R's own sapply. This has been implicitly FALSE in Rmpfr versions 0.8-5 to 0.8-9 (Oct 2021 to June 2022), accidentally. Since Rmpfr 0.9-0, this has been made an argument with default TRUE to be compatible by default with R's sapply.

Author

Martin Maechler

Details

In the case FUN(<length-1>) returns an array or "mpfrArray", i.e., with two or more dimensions, sapplyMpfr() returns an "mpfrArray"; this is analogous to sapply(X, FUN, simplify = "array") (rather than the default sapply() behaviour which returns a matrix also when a higher array would be more “logical”.)

See Also

sapply, lapply, etc.

Examples

sapplyMpfr0 <- ## Originally, the function was simply defined as
  function (X, FUN, ...) new("mpfr", unlist(lapply(X, FUN, ...), recursive = FALSE))

(m1 <- sapply    (     3,      function(k) (1:3)^k)) # 3 x 1  matrix (numeric)
(p1 <- sapplyMpfr(mpfr(3, 64), function(k) (1:3)^k))
stopifnot(m1 == p1, is(p1, "mpfrMatrix"), dim(p1) == c(3,1), dim(p1) == dim(m1))
k.s <- c(2, 5, 10, 20)
(mk <- sapply    (     k.s,      function(k) (1:3)^k)) # 3 x 4    "       "
(pm <- sapplyMpfr(mpfr(k.s, 64), function(k) (1:3)^k))
stopifnot(mk == pm, is(pm, "mpfrMatrix"), dim(pm) == 3:4, 3:4 == dim(mk))
## was *wrongly* 4x3  in Rmpfr 0.8-x
f5k  <- function(k) outer(1:5, k+0:2, `^`)# matrix-valued
(mk5 <- sapply    (     k.s,      f5k))  # sapply()'s default; not "ideal"
(ak5 <- sapply    (     k.s,      f5k, simplify = "array")) # what we want
(pm5 <- sapplyMpfr(mpfr(k.s, 64), f5k))
stopifnot(c(mk5) == c(ak5), ak5 == pm5, is(pm5, "mpfrArray"), is.array(ak5),
          dim(pm5) == dim(ak5), dim(pm5) == c(5,3, 4))
if(require("Bessel")) { # here X, is simple
  bI1 <- function(k) besselI.nuAsym(mpfr(1.31e9, 128), 10, expon.scaled=TRUE, k.max=k)
  bImp1 <- sapplyMpfr (0:4, bI1, drop_1_ = FALSE) # 1x5 mpfrMatrix -- as in DPQ 0.8-8
  bImp  <- sapplyMpfr (0:4, bI1, drop_1_ = TRUE ) # 5 "mpfr" vector {by default}
  bImp0 <- sapplyMpfr0(0:4, bI1) # 5-vector
  stopifnot(identical(bImp, bImp0), bImp == bImp1,
            is(bImp, "mpfr"), is(bImp1, "mpfrMatrix"), dim(bImp1) == c(1, 5))
}# {Bessel}