Function integrate_2d 

pub fn integrate_2d<F: FnMut(f64, f64) -> f64>(
    f: F,
    u: (f64, f64),
    v: (f64, f64),
    tolerance: f64,
) -> OgeomResult<f64>

Integrate f(u, v) over the rectangle [a, b] x [c, d] to an absolute tolerance: a patch’s area, its moments, anything spread over a chart.

The Gauss-Kronrod pair in tensor form: one pass over a cell is fifteen by fifteen evaluations and yields the Kronrod estimate and, from the same values, the estimate with the Gauss rule in u and the one with it in v, each gap the error attributed to that direction. A cell whose worse gap is inside its budget is done. One whose is not is halved along the rougher direction, each half given half the budget, so the cells’ errors sum to the whole’s and a ridge running across the chart (a crease in an integrand, a seam) costs a line of cells rather than a field of them.

Errors

OgeomError::Domain if a bound is not finite or the tolerance is not positive; OgeomError::NotDone if some cell did not converge within the depth limit.