POLY Function

Standard Library function that evaluates a polynomial function of a variable.

result = POLY(x, coefficients)

x The variable that is evaluated. May be a scalar or array.

coefficients A vector containing one more element than the degree of the polynomial function. These elements are the coefficients of the polynomial equation that is used by POLY.

result The values calculated from the polynomial function of x.

None.

POLY evaluates a polynomial function of a variable according to the formula:

result = c₀ + c₁x + c₂x² + ... + c_n-1x^n-1

where n is the dimension of the polynomial c, and c₀ through c_n-1 are the coefficients.

POLY returns a variable with the same dimensions as x. Each element of the result is equal to the computed value of c₀ + c₁x + c₂x² + c_ixⁱ for each element of x.

The POLY function can be used in conjunction with POLY_FIT and POLYFITW, which both return the coefficients of a polynomial function fitted through data.

x = 2
c = [1, 2, 3]
func = POLY(x, c)
PRINT, func

POLY_2D, POLY_FIT, POLYFITW