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pub mod trf;
pub mod trs;

use crate::matrix::*;
use crate::number::Number;

#[derive(Clone, Debug, Default, Hash)]
pub struct TridiagonalMatrix<T = f64>
where
    T: Number,
{
    dl: Vec<T>,
    d: Vec<T>,
    du: Vec<T>,
}

impl<T> TridiagonalMatrix<T>
where
    T: Number,
{
    pub fn new(dl: Vec<T>, d: Vec<T>, du: Vec<T>) -> Result<Self, MatrixError> {
        let n_1 = d.len().max(1) - 1;
        if n_1 != dl.len() || n_1 != du.len() {
            return Err(MatrixError::DimensionMismatch);
        }

        Ok(Self { dl, d, du })
    }

    pub fn dl(&self) -> &[T] {
        &self.dl
    }

    pub fn d(&self) -> &[T] {
        &self.d
    }

    pub fn du(&self) -> &[T] {
        &self.du
    }

    pub fn elems(self) -> (Vec<T>, Vec<T>, Vec<T>) {
        (self.dl, self.d, self.du)
    }

    pub fn mat(&self) -> Matrix<T> {
        let n = self.d.len();
        let mut mat = Matrix::new(n, n);

        for i in 0..n {
            mat[i][i] = self.d[i];
        }

        for i in 0..n - 1 {
            mat[i][i + 1] = self.du[i];
            mat[i + 1][i] = self.dl[i];
        }

        mat
    }
}