Function integrate_1d 

pub fn integrate_1d<F: Fn(f64) -> f64>(
    f: F,
    a: f64,
    b: f64,
    opts: VegasOptions,
) -> IntegrateResult

Numerically integrate a one-dimensional function f over [a, b] using Vegas with default options. Returns the estimate and standard error.

The integrand receives x directly (not a unit-hypercube coordinate): the linear change of variables is applied internally, so jacobian = (b − a) is folded into the result.

use ocas_eval::numeric::integrate_1d;

let r = integrate_1d(|x| x, 0.0, 1.0, Default::default());
assert!((r.integral - 0.5).abs() < 0.01);