inv_poly: Polynomial Functions

In flexmet: Flexible Latent Trait Metrics using the Filtered Monotonic Polynomial Item Response Model

Description

Evaluate a forward or inverse (monotonic) polynomial function.

Usage

inv_poly(x, coefs, lb = -1000, ub = 1000)

fw_poly(y, coefs)

Arguments

x	Scalar polynomial function input.
coefs	Vector of coefficients that define a monotonic polynomial, see details.
lb	Lower bound of the search interval.
ub	Upper bound of the search interval.
y	Scalar polynomial function output.

Details

x = t0 + t1*y + t2*y^2 + ...

Then, for coefs = (t0, t1, t2, ...)', this function finds the corresponding y value (inv_poly) or x value (fw_poly).

flexmet documentation built on July 14, 2021, 1:06 a.m.