TY - GEN AU - John Gregg Lewis AU - Ronald G Rehm C2 - , National Institute of Standards and Technology, Gaithersburg, MD DA - 1980-01-01 05:01:00 DO - https://doi.org/10.6028/NBS.IR.80-2056 LA - en PB - , National Institute of Standards and Technology, Gaithersburg, MD PY - 1980 TI - The numerical solution of a nonseparable elliptic partial differential equation by preconditioned conjugate gradients: ER -