Convert between multipol and list representations of multivariate polynomials

Description

Converts an multipol object to a simple list representing a multivariate polynomial or a simple list to an multipol object

Usage

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convert.multipol(poly)

Arguments

poly

a multipol object or a list giving powers and coefficients defining the polynomial

Details

The list representation consists of 2 components: 'powers' is a matrix with each row representing the powers of X in one term of the multivariate polynomial. 'coeff' is a vector with each element being the coefficient of the corresponding term in powers

Value

if poly is of class 'multipol', it is a list with two components described below. If poly is such a list, the value is the corresponding multipol object

Author(s)

Kem Phillips <kemphillips@comcast.net>

References

K Phillips, Symbolic Computation of the Central Moments of the Multivariate Normal Distribution, Journal of Statistical Software, 2010.

See Also

convert.multipol, evaluate.expected.polynomial, integrate.polynomial

Examples

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# create an mpoly object to work with
library(mpoly)
t0 <- mpoly(list(c(coef=3,x1=2),c(coef=2,x1=1,x2=3),
                   c(coef=-4,z=2),c(coef=1,x1=1,x2=2,z=1))) 

# convert from mpoly to list representation
t1 <- convert.mpoly(t0)    
# convert from list representation to a multipol object
t2 <- convert.multipol(t1) 
# convert back to a list representation
t3 <- convert.multipol(t2)