Function tridiagonal_csc 

pub fn tridiagonal_csc(
    diagonal: &[f64],
    lower: &[f64],
    upper: &[f64],
) -> IterSolverResult<CscMatrix<f64>>

Creates a tridiagonal sparse CSC matrix from diagonal, lower diagonal, and upper diagonal vectors.

This function constructs a tridiagonal matrix where:

• The main diagonal contains elements from the diagonal vector
• The lower-diagonal (below main) contains elements from the lower vector
• The upper-diagonal (above main) contains elements from the upper vector

Arguments

• diagonal - A slice containing the main diagonal elements
• lower - A slice containing the lower diagonal elements (lower-diagonal)
• upper - A slice containing the upper diagonal elements (upper-diagonal)

Dimension Requirements

For a valid tridiagonal matrix:

• diagonal.len() must equal lower.len() + 1
• lower.len() must equal upper.len()

This is because an n×n tridiagonal matrix has:

• n diagonal elements
• (n-1) lower-diagonal elements
• (n-1) upper-diagonal elements

Examples

use iterative_solvers::utils::sparse::tridiagonal_csr;

let diagonal = vec![2.0, 3.0, 4.0];
let lower = vec![1.0, 1.0];
let upper = vec![1.0, 1.0];

let result = tridiagonal_csr(&diagonal, &lower, &upper).unwrap();
// Creates:
// [2.0, 1.0, 0.0]
// [1.0, 3.0, 1.0]
// [0.0, 1.0, 4.0]

Errors

Returns IterSolverError::DimensionError if the input vectors have incompatible dimensions.