Constructor, coercion, predicate and print functions for polynom and polylist objects

Description

The function polynom is the constructor function for objects of the eponymous S3 class. as.polynom is the standad coercion function to the same class and is.polynom tests for inheritance from the class. polylist objects are lists of polynom objects, again with the eponymous class.

Usage

polynom(a = c(0, 1), ..., eps = 0)
as.polynom(a)
is.polynom(a)
polylist(...)
as.polylist(x)
is.polylist(x)
## S3 method for class 'polynom'
print(x, variable = "x",
   digits = getOption("digits"), decreasing = FALSE, ...)
## S3 method for class 'polylist'
print(x, ...) 

Arguments

Details

polynom objects are represented as R functions with the coefficient vector held in an enclosing environment, or closure. They may be used as R functions, or as mathematical objects which behave under arithmetic and calculus operatons like polynomials.

Note that polynomials with complex coefficients are not (yet) supported. Nevertheless the root-finding methods described elsewhere will usually give complex zeros.

polylist objects are lists of polynom objects. Methods are available for dealing with all polynomials on the list simultaneously.

Value

For polynom and as.polynom, an R function with class polynom. For is.polynom, a logical value

Author(s)

Bill Venables

References

None

Examples

x <- polynom()  # polynomial 'x'
p <- (x-1)^2 + 10*x^3 + 5*x^4
p
# 1 - 2*x + x^2 + 10*x^3 + 5*x^4 

plot(polylist(p, deriv(p), integral(p)),
    xlim = c(-2, 1), ylim = c(-10, 10))
abline(h=0, lty = "dashed", col = "grey")

print(p, variable = "z", decreasing = TRUE)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(PolynomF)
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/PolynomF/polynom.Rd_%03d_medium.png", width=480, height=480)
> ### Name: polynom
> ### Title: Constructor, coercion, predicate and print functions for polynom
> ###   and polylist objects
> ### Aliases: polynom as.polynom is.polynom polylist as.polylist is.polylist
> ###   print.polynom print.polylist
> ### Keywords: symbolmath
> 
> ### ** Examples
> 
> x <- polynom()  # polynomial 'x'
> p <- (x-1)^2 + 10*x^3 + 5*x^4
> p
1 - 2*x + x^2 + 10*x^3 + 5*x^4 
> # 1 - 2*x + x^2 + 10*x^3 + 5*x^4 
> 
> plot(polylist(p, deriv(p), integral(p)),
+     xlim = c(-2, 1), ylim = c(-10, 10))
> abline(h=0, lty = "dashed", col = "grey")
> 
> print(p, variable = "z", decreasing = TRUE)
5*z^4 + 10*z^3 + z^2 - 2*z + 1 
> 
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>