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diff --git a/src/main/java/org/apache/commons/math3/linear/IterativeLinearSolverEvent.java b/src/main/java/org/apache/commons/math3/linear/IterativeLinearSolverEvent.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.linear;
+
+import org.apache.commons.math3.exception.MathUnsupportedOperationException;
+import org.apache.commons.math3.util.IterationEvent;
+
+/**
+ * This is the base class for all events occurring during the iterations of a {@link
+ * IterativeLinearSolver}.
+ *
+ * @since 3.0
+ */
+public abstract class IterativeLinearSolverEvent extends IterationEvent {
+    /** Serialization identifier. */
+    private static final long serialVersionUID = 20120129L;
+
+    /**
+     * Creates a new instance of this class.
+     *
+     * @param source the iterative algorithm on which the event initially occurred
+     * @param iterations the number of iterations performed at the time {@code this} event is
+     *     created
+     */
+    public IterativeLinearSolverEvent(final Object source, final int iterations) {
+        super(source, iterations);
+    }
+
+    /**
+     * Returns the current right-hand side of the linear system to be solved. This method should
+     * return an unmodifiable view, or a deep copy of the actual right-hand side vector, in order
+     * not to compromise subsequent iterations of the source {@link IterativeLinearSolver}.
+     *
+     * @return the right-hand side vector, b
+     */
+    public abstract RealVector getRightHandSideVector();
+
+    /**
+     * Returns the norm of the residual. The returned value is not required to be <em>exact</em>.
+     * Instead, the norm of the so-called <em>updated</em> residual (if available) should be
+     * returned. For example, the {@link ConjugateGradient conjugate gradient} method computes a
+     * sequence of residuals, the norm of which is cheap to compute. However, due to accumulation of
+     * round-off errors, this residual might differ from the true residual after some iterations.
+     * See e.g. A. Greenbaum and Z. Strakos, <em>Predicting the Behavior of Finite Precision Lanzos
+     * and Conjugate Gradient Computations</em>, Technical Report 538, Department of Computer
+     * Science, New York University, 1991 (available <a
+     * href="http://www.archive.org/details/predictingbehavi00gree">here</a>).
+     *
+     * @return the norm of the residual, ||r||
+     */
+    public abstract double getNormOfResidual();
+
+    /**
+     * Returns the residual. This is an optional operation, as all iterative linear solvers do not
+     * provide cheap estimate of the updated residual vector, in which case
+     *
+     * <ul>
+     *   <li>this method should throw a {@link MathUnsupportedOperationException},
+     *   <li>{@link #providesResidual()} returns {@code false}.
+     * </ul>
+     *
+     * <p>The default implementation throws a {@link MathUnsupportedOperationException}. If this
+     * method is overriden, then {@link #providesResidual()} should be overriden as well.
+     *
+     * @return the updated residual, r
+     */
+    public RealVector getResidual() {
+        throw new MathUnsupportedOperationException();
+    }
+
+    /**
+     * Returns the current estimate of the solution to the linear system to be solved. This method
+     * should return an unmodifiable view, or a deep copy of the actual current solution, in order
+     * not to compromise subsequent iterations of the source {@link IterativeLinearSolver}.
+     *
+     * @return the solution, x
+     */
+    public abstract RealVector getSolution();
+
+    /**
+     * Returns {@code true} if {@link #getResidual()} is supported. The default implementation
+     * returns {@code false}.
+     *
+     * @return {@code false} if {@link #getResidual()} throws a {@link
+     *     MathUnsupportedOperationException}
+     */
+    public boolean providesResidual() {
+        return false;
+    }
+}