# Symmetry

The APM solver supports symmetry solutions across the x-z plane. When using the symmetry option the solver calculates the influence coefficients 2x faster and requires 2x less memory. To enable the symmetry option, set the `symmetry` option to 1 in the **.conf** file. Note that any motion that you prescribe (if performing an unsteady simulation) must honour the x-z symmetry requirements. This means no velocity components in the y-direction or non-zero sideslip angle! The image below shows the comparison of the wake between symmetric and non-symmetric solutions.

<figure><img src="/files/IC7H0tmTtqx5x5kRZe2X" alt=""><figcaption><p>Symmetric and non-symmetric (not assuming) symmetry of a fixed-wing UAV.</p></figcaption></figure>


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