# writemat

This controls the output of the mathematical operators in the Poisson-Boltzmann equation as matrices in Harwell-Boeing matrix format (multigrid only). The syntax is:

    writemat {type} {stem}

where

`type`

  A string that indicates what type of operator to output.

  `poisson`
    Write out the Poisson operator \(-\nabla \cdot \epsilon \nabla\).
`stem`
  A string that specifies the path for the output.