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- let eps = 1e-10
- fn diff(f: Fn[(Scalar) -> Scalar], x: Scalar) -> Scalar =
- (f(x + eps) - f(x)) / eps
- assert_eq(diff(log, 2.0), 1 / 2, 1e-5)
- assert_eq(diff(sin, 0.0), 1.0, 1e-5)
- fn f(x: Scalar) -> Scalar = x * x + 4 * x + 1
- assert_eq(diff(f, 2.0), 8.0, 1e-5)
- # TODO: It would be so cool if we could write it in a generic way:
- #
- # fn diff<X, Y>(f: Fn[(X) -> Y], x: X) -> Y / X =
- # (f(x + eps · unit_of(x)) - f(x)) / (eps · unit_of(x))
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