[Doc] added formulae

Documentation/ProjectFile/process/convergence_criterion/DeltaX/c_DeltaX.md

@@ -6,4 +6,6 @@ the norm of the whole solution vector, i.e., the entirety of all process
 variables.
 
 At least one of the relative or absolute tolerance has to be met in order to
-satisfy this convergence criterion.
+satisfy this convergence criterion, i.e., the following has to hold (with errors
+\f$e\f$ and tolerances \f$t\f$):
+\f[ e_{\mathrm{abs}} \le t_{\mathrm{abs}} \vee e_{\mathrm{rel}} \le t_{\mathrm{rel}} \f]

Documentation/ProjectFile/process/convergence_criterion/PerComponentDeltaX/c_PerComponentDeltaX.md

@@ -7,4 +7,6 @@ vectorial process variable, to each vector component) of the solution vector
 individually.
 
 For each component at least one of the relative or absolute tolerance has to be
-met in order to satisfy this convergence criterion.
+met in order to satisfy this convergence criterion, i.e., the following has to
+hold (with errors \f$e\f$ and tolerances \f$t\f$):
+\f[ e_{\mathrm{abs}} \le t_{\mathrm{abs}} \vee e_{\mathrm{rel}} \le t_{\mathrm{rel}} \f]

Documentation/ProjectFile/process/convergence_criterion/PerComponentResidual/c_PerComponentResidual.md

@@ -7,4 +7,6 @@ vectorial process variable, to each vector component) of the residuum vector
 individually.
 
 For each component at least one of the relative or absolute tolerance has to be
-met in order to satisfy this convergence criterion.
+met in order to satisfy this convergence criterion, i.e., the following has to
+hold (with errors \f$e\f$ and tolerances \f$t\f$):
+\f[ e_{\mathrm{abs}} \le t_{\mathrm{abs}} \vee e_{\mathrm{rel}} \le t_{\mathrm{rel}} \f]

Documentation/ProjectFile/process/convergence_criterion/Residual/c_Residual.md

@@ -5,4 +5,6 @@ A relative and/or absolute tolerance value can be specified, which is applied to
 the norm of the whole residuum vector.
 
 At least one of the relative or absolute tolerance has to be met in order to
-satisfy this convergence criterion.
+satisfy this convergence criterion, i.e., the following has to hold (with errors
+\f$e\f$ and tolerances \f$t\f$):
+\f[ e_{\mathrm{abs}} \le t_{\mathrm{abs}} \vee e_{\mathrm{rel}} \le t_{\mathrm{rel}} \f]