# 4.9.7. Nonlinear Iteration Settings

The solution options block is where you can define the number of nonlinear iterations and convergence criteria for your active equations. The default nonlinear residual norm tolerance is very small () so if you do not specify it, Fuego will generally just do the maximum number of iterations defined by `Maximum Number of Nonlinear iterations`. Note that these residuals are dimensional, so scaling a problem from meters to centimeters would require different residual targets to maintain the same behavior.

    Begin Solution Options

      Minimum Number of Nonlinear iterations = 2
      Maximum Number of Nonlinear iterations = 4

      Nonlinear Residual Norm Tolerance = 1e-6 for Equation Continuity
      Nonlinear Residual Norm Tolerance = 1e-6 for Equation X_Momentum
      Nonlinear Residual Norm Tolerance = 1e-6 for Equation Y_Momentum
      Nonlinear Residual Norm Tolerance = 1e-6 for Equation Z_Momentum

You can also control iterations of groups of related equations, which by default only take one iteration per group.

    Begin Solution Options

      Maximum Number of Continuity_Momentum Nonlinear Iterations = 3

The sub-groups available to iterate with this command are:

> - `CONTINUITY_MOMENTUM`

> - `SPECIES`

> - `SPECIES_PRODUCT`

> - `ENERGY_SPECIES`

> - `SOLID PHASE`

> - `GAS_SOLID_MOMENTUM`

> - `MIXTURE FRACTION`

> - `SOOT NUCLEI`

> - `KEPSILON`

> - `KSGS`

> - `V2F`

> - `KOMEGA`