Add EC trait function to adjust code parameter after selection

resource_estimator/src/estimates/error_correction.rs

@@ -156,6 +156,22 @@ pub trait ErrorCorrection {
             .ok_or_else(|| format!("No code parameter achieves required logical error rate {required_logical_error_rate:.3e}"))
     }
 
+    /// Adjusts code parameter after computing it
+    ///
+    /// This function is called after the initial code parameter has been
+    /// computed.  The initial code parameter will fit the required logical
+    /// error rate, but it's possible to further refine it, if necessary.
+    ///
+    /// Note, that when implementing the `ErrorCorrection` trait and providing a
+    /// custom implementation for this function, it may return a code parameter
+    /// that will not fit the required logical error rate any longer.
+    ///
+    /// The default implementation does not update the code parameter.
+    fn adjust_code_parameter(&self, parameter: Self::Parameter) -> Result<Self::Parameter, String> {
+        // Default implementation does not update the code parameter
+        Ok(parameter)
+    }
+
     /// Returns an iterator of all possible code parameters
     ///
     /// Implementors of this method should sort the code parameters such that

resource_estimator/src/estimates/physical_estimation.rs

@@ -558,8 +558,13 @@ impl<
 
     /// Computes the code parameter for the required logical error rate
     fn compute_code_parameter(&self, error_rate: f64) -> Result<E::Parameter, Error> {
-        self.ftp
+        let parameter = self
+            .ftp
             .compute_code_parameter(&self.qubit, error_rate)
+            .map_err(Error::CodeParameterComputationFailed)?;
+
+        self.ftp
+            .adjust_code_parameter(parameter)
             .map_err(Error::CodeParameterComputationFailed)
     }