** Next:** Activation of physical processes
** Up:** Choice of grids, time
** Previous:** Computational grids and boundary
** Index**

SWAN can provide output on uniform, rectilinear spatial grids that are independent from the input grids
and from the computational grid. In the computation with a curvilinear computational grid, curvilinear
output grids are available in SWAN. This also holds for triangular meshes.
An output grid has to be specified by the user with an arbitrary
resolution, but it is of course wise to choose a resolution that is fine enough to show relevant spatial
details. It must be pointed out that the information on an output grid is obtained from the computational
grid by bi-linear interpolation (output always at computational time level). This implies that some
inaccuracies are introduced by this interpolation. It also implies that bottom or current information on an
output plot has been obtained by interpolating twice: once from the input grid to the computational grid
and once from the computational grid to the output grid. If the input-, computational- and output grids are
identical, then no interpolation errors occur.

In the regions where the output grid does not cover the computational grid, SWAN assumes output values
equal to the corresponding exception value. For example, the default exception value for the significant
wave height is -9. The exception values of output quantities can be changed by means of the `QUANTITY`
command.

In nonstationary computations, output can be requested at regular intervals starting at a given time
always at computational times.

** Next:** Activation of physical processes
** Up:** Choice of grids, time
** Previous:** Computational grids and boundary
** Index**
The SWAN team 2017-07-31