dex: dex

In nlsr: Functions for Nonlinear Least Squares Solutions - Updated 2022

dex

Description

Calculate expression for derivative calculations. Mainly for internal use, dex() converts its input to an expression suitable for use in nlsDeriv and related functions.

Usage

dex(x, do_substitute = NA, verbose = FALSE)

Arguments

x	An expression represented in a variety of ways. See Details.
do_substitute	Whether to use the expression passed as x, or to evaluate it and use its value.
verbose	Print messages describing the process.

Details

If do_substitute is NA, the following rules are used:

• An attempt is made to evaluate x. If that fails, the expression is used.

• If the evaluation succeeds and the value is a character vector, it is parsed.

• If the value is not a character vector and the expression is a single name, the value is used.

Otherwise, the expression is used.

Once the expression is determined it may be simplified, by extracting the language object from a length-one expression vector, or the right-hand-side from a formula.

Normally a warning will be issued if x is a formula containing a left-hand side. To suppress this, wrap the formula in expression(), or pass it as a character string to be parsed.

value

An expression or language object suitable as input to nlsDeriv and related functions.

Author(s)

Duncan Murdoch

Examples

   aa <- dex(~ x^2)
   aa
   str(aa)
   bb <- dex(expression(x^2))
   bb
   str(bb)
   cc <- dex("x^2")
   cc
   str(cc)
   

nlsr documentation built on Sept. 8, 2023, 5:48 p.m.