Function triangle_duffy_gauss_legendre 

pub fn triangle_duffy_gauss_legendre(
    points_per_axis: usize,
) -> Result<QuadratureRule, Diagnostic>

Construct the positive Duffy–Gauss–Legendre rule on the unit triangle.

This compatibility name delegates to the runtime-dimensional simplex family and retains the established 2n - 2 exactness contract.

Errors

Preserves simplex_duffy_gauss_legendre’s errors for dimension two.