Coerce a Polynomial to a Function
Takes a polynomial argument and constructs an R function to evaluate it at arbitrary points.
## S3 method for class 'polynomial' as.function(x, ...)
x |
An object of class |
... |
further arguments to be passed to or from methods. |
This is a method for the generic function as.function.
The polynomial is evaluated within the function using the Horner scheme.
Note that you can use the model-oriented predict method for
polynomials for purpose of evaluation (without explicit coercion to
a function), see the example below.
A function to evaluate the polynomial p.
pr <- (poly.calc(-1:1) - 2 * polynomial(c(1, 2, 1)))^2 pr ## 4 + 20*x + 33*x^2 + 16*x^3 - 6*x^4 - 4*x^5 + x^6 prf <- as.function(pr) prf ## function (x) ## 4 + x * (20 + x * (33 + x * (16 + x * (-6 + x * (-4 + x * (1)))))) ## <environment: 0x402440f0> prf(-3:3) ## 1024 64 0 4 64 144 64 predict(pr, -3:3) ## 1024 64 0 4 64 144 64
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