Ops.multipol {multipol}

Arithmetic ops group methods for multipols

Description

Allows arithmetic operators to be used for multivariate polynomials such as addition, multiplication, and integer powers.

Usage

## S3 method for class 'multipol'
Ops(e1, e2 = NULL)
mprod(...,  trim = TRUE , maxorder=NULL)
mplus(...,  trim = TRUE , maxorder=NULL)
 mneg(a,    trim = TRUE , maxorder=NULL)
  mps(a, b, trim = TRUE , maxorder=NULL)
 mpow(a, n, trim = TRUE , maxorder=NULL)

Arguments

e1, e2, a

Multipols; scalars coerced

b

Scalar

n

Integer power

...

Multipols

trim

Boolean, with default TRUE meaning to return a trim()-ed multipol and FALSE meaning not to trim

maxorder

Numeric vector indicating maximum orders of the output [that is, the highest power retained in the multivariate Taylor expansion about rep(0,d)]. Length-one input is recycled to length d; default value of NULL means to return the full result. More details given under taylor()

Details

The function Ops.multipol() passes unary and binary arithmetic operators (“+”, “-”, “*”, and “^”) to the appropriate specialist function.

In multipol.R, these specialist functions all have formal names such as .multipol.prod.scalar() which follow a rigorous pattern; they are not intended for the end user. They are not exported from the namespace as they begin with a dot.

Five conveniently-named functions are provided in the package for the end-user; these offer greater control than the arithmetic command-line operations in that arguments trim or maxorder may be set. They are:

• mprod() for products,

• mplus() for addition,

• mneg() for the negative,

• mps() for adding a scalar,

• mpow() for powers.

Addition and multiplication of multivariate polynomials is commutative and associative, to machine precision.

Author(s)

Robin K. S. Hankin

See Also

outer,trim,taylor

Examples

a <- as.multipol(matrix(1,4,5))
100+a

f <- as.function(a+1i)
f(5:6)


b <- as.multipol(array(rnorm(12),c(2,3,2)))

f1 <- as.function(b)
f2 <- as.function(b*b)
f3 <- as.function(b^3)    # could have said b*b*b

x <- c(1,pi,exp(1))

f1(x)^2 - f2(x)    #should be zero
f1(x)^3 - f3(x)    #should be zero

x1 <- as.multipol(matrix(1:10,ncol=2))
x2 <- as.multipol(matrix(1:10,nrow=2))
x1+x2