hpa (version 1.0.1)

polynomialIndex: Returns matrix of polynomial indexes

Description

Returns matrix of polynomial indexes for the polynomial with degrees (orders) vector pol_degrees.

Usage

polynomialIndex(pol_degrees = 0L)

Arguments

pol_degrees

non-negative integer vector of polynomial degrees.

Value

This function returns polynomial indexes matrix which rows are responsible for variables while columns are related to powers.

Details

This function motivation is to have an opportunity to iterate through the columns of polynomial indexes matrix in order to access polynomial elements being aware of their powers.

Examples

# NOT RUN {
## Get polynomial indexes matrix for the polynomial which degrees are (1, 3, 5)

polynomialIndex(c(1, 3, 5))

# }
# NOT RUN {
## Consider polynomial of degrees (2, 1) such that coefficients
## for elements which powers sum is even are 2 and for those which powers
## are odd are 5. So the polynomial is 2+5y+5x+2xy+2x^2+5yx^2.

# Let's represent its powers (not coefficients) in a matrix form
pol_matrix <- polynomialIndex(c(2, 1))

# Suppose we want to calculate this polynomial coefficients sum:
powers_sum <- 0

# For pedagogical reasons iterate throught the pol_matrix columns
pol_matrix_length = dim(pol_matrix)[2]

for (i in 1:pol_matrix_length) 
{
	if ((pol_matrix[1, i] + pol_matrix[2, i]) %% 2 == 0)
	{
	  powers_sum <- powers_sum + 2
	} else {
	  powers_sum <- powers_sum + 5
	}
}
#powers_sum value will be 21
# }