PSPexpression {qspray}

Symmetric polynomial in terms of the power sum polynomials

Description

Expression of a symmetric qspray polynomial as a polynomial in the power sum polynomials.

Usage

PSPexpression(qspray)

Arguments

qspray

a symmetric qspray polynomial; symmetry is not checked

Value

A qspray polynomial, say P, such that P(p_1, ..., p_n) equals the input symmetric polynomial, where p_i is the i-th power sum polynomial (PSFpoly(n, i)).

See Also

PSPcombination

Examples

# take a symmetric polynomial
( qspray <- ESFpoly(4, c(2, 1)) + ESFpoly(4, c(2, 2)) )
# compute the power sum expression
( pspExpr <- PSPexpression(qspray) )
# take the involved power sum polynomials
psPolys <- lapply(1:numberOfVariables(pspExpr), function(i) PSFpoly(4, i))
# then this should be TRUE:
qspray == changeVariables(pspExpr, psPolys)