I'm trying to complete a straightforward integration, but I'm running into an issue that (I think) is due to the form in which I'm writing the integrand.
Suppose I want to find the area bound by f(x) = 3x and g(x) = x^2. Geometrically, the area between the two curves:
Ok, so not a big deal to do analytically:
But I'd like to accomplish this with R, of course.
So I enter my function and there's a problem:
> g <- function(x) {3x-x^2}
Error: unexpected symbol in "g <- function(x) {3x"
This frustrated me so I started playing around with things. Interestingly, I found that if I factor x out of the integrand:
everything works smoothly:
> f <- function(x) {x*(3-x)}
> integrate(f, 0, 3)
4.5 with absolute error < 5e-14
My next step was to check ?integrate, part of which is attached below:
integrate(f, lower, upper, ..., subdivisions = 100L, rel.tol = .Machine$double.eps^0.25, abs.tol = rel.tol, stop.on.error = TRUE, keep.xy = FALSE, aux = NULL) Arguments
f
an R function taking a numeric first argument and returning a numeric vector of the same length. Returning a non-finite element will generate an error.lower, upper
the limits of integration. Can be infinite.
Am I somehow not taking a numeric first argument in my first attempt to integrate? Thanks in advance.
