fn spd_solve(a: &[f64], n: usize, b: &[f64], k: usize) -> Vec<f64>
Solve the SPD system A X = B via Cholesky. a is row-major n × n, b is row-major n × k; returns X row-major n × k. A is never inverted.
A X = B
a
n × n
b
n × k
X
A