# Solver NOTES

From ASCEND

*Using solver NOTES is no longer the preferred approach to solving this problem. We now suggest you use the OPTION command, even though it is still somewhat experimental.*

Solver NOTES are a special kind of NOTES in ASCEND that allow you to specify parameters for use in the solver when running a particular model. This uses the ExtPy mechanism, which isn't yet considered stable.

To use solver notes, try

IMPORT "johnpye/solvernotes"; ADD NOTES IN mymodel; 'solver' name {QRSlv} 'QRSlv' iterationlimit {50} 'QRSlv' singtol {1e-10} END NOTES; MODEL mymodel; x, y IS_A solver_var; x = y^2; METHODS METHOD on_load; EXTERNAL solvernotes(SELF); END on_load; END mymodel;

The above specifies that the preferred solver for the model `mymodel` is QRSlv, then sets the `iterationlimit` and `singtol` parameters when using that solver. The external method, `solvernotes` must be `IMPORT`ed, and called using the `EXTERNAL` statement.