Solving Sparse Symmetric Sets of Linear Equations by Preconditioned Conjugate Gradients.

N. Munksgaard Solving Sparse Symmetric Sets of Linear Equations by Preconditioned Conjugate Gradients. 206-219 1980 6 ACM Trans. Math. Softw. 2 https://doi.org/10.1145/355887.355893 db/journals/toms/toms6.html#Munksgaard80