. Author manuscript; available in PMC: 2020 Apr 15.

Published in final edited form as: J Comput Phys. 2019 Feb 1;383:72–93. doi: 10.1016/j.jcp.2019.01.019

Algorithm 2.

The multiplication of S with a vector x_p.

1: Compute the matrix-vector multiplication

{\hat{x}}_{p} \leftarrow D x_{p} .

2: Compute the matrix-vector multiplication

{\bar{x}}_{p} \leftarrow B x_{p} .

3: Solve for

{\tilde{x}}_{p}

from the linear system

A {\tilde{x}}_{p} = {\bar{x}}_{p} .

(4.6)

4: Compute the matrix-vector multiplication

{\bar{x}}_{p} \leftarrow C {\tilde{x}}_{p} .

5: return ${\hat{x}}_{p} - {\bar{x}}_{p} .$