Function matrix_from_gauss 

pub fn matrix_from_gauss<T, K>(
    kernel: &K,
    gauss_x: &Rule<T>,
    gauss_y: &Rule<T>,
    symmetry: SymmetryType,
) -> DiscretizedKernel<T>
where
    T: CustomNumeric + Clone,
    K: CentrosymmKernel + KernelProperties,

Compute matrix from Gauss quadrature rules (legacy version without segments)

This function evaluates the kernel at all combinations of Gauss points and returns a DiscretizedKernel containing the matrix and quadrature rules.