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diff --git a/src/main/java/org/apache/commons/math3/stat/descriptive/StorelessUnivariateStatistic.java b/src/main/java/org/apache/commons/math3/stat/descriptive/StorelessUnivariateStatistic.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.stat.descriptive;
+
+import org.apache.commons.math3.exception.MathIllegalArgumentException;
+
+/**
+ * Extends the definition of {@link UnivariateStatistic} with
+ * {@link #increment} and {@link #incrementAll(double[])} methods for adding
+ * values and updating internal state.
+ * <p>
+ * This interface is designed to be used for calculating statistics that can be
+ * computed in one pass through the data without storing the full array of
+ * sample values.</p>
+ *
+ */
+public interface StorelessUnivariateStatistic extends UnivariateStatistic {
+
+    /**
+     * Updates the internal state of the statistic to reflect the addition of the new value.
+     * @param d  the new value.
+     */
+    void increment(double d);
+
+    /**
+     * Updates the internal state of the statistic to reflect addition of
+     * all values in the values array.  Does not clear the statistic first --
+     * i.e., the values are added <strong>incrementally</strong> to the dataset.
+     *
+     * @param values  array holding the new values to add
+     * @throws MathIllegalArgumentException if the array is null
+     */
+    void incrementAll(double[] values) throws MathIllegalArgumentException;
+
+    /**
+     * Updates the internal state of the statistic to reflect addition of
+     * the values in the designated portion of the values array.  Does not
+     * clear the statistic first -- i.e., the values are added
+     * <strong>incrementally</strong> to the dataset.
+     *
+     * @param values  array holding the new values to add
+     * @param start  the array index of the first value to add
+     * @param length  the number of elements to add
+     * @throws MathIllegalArgumentException if the array is null or the index
+     */
+    void incrementAll(double[] values, int start, int length) throws MathIllegalArgumentException;
+
+    /**
+     * Returns the current value of the Statistic.
+     * @return value of the statistic, <code>Double.NaN</code> if it
+     * has been cleared or just instantiated.
+     */
+    double getResult();
+
+    /**
+     * Returns the number of values that have been added.
+     * @return the number of values.
+     */
+    long getN();
+
+    /**
+     * Clears the internal state of the Statistic
+     */
+    void clear();
+
+    /**
+     * Returns a copy of the statistic with the same internal state.
+     *
+     * @return a copy of the statistic
+     */
+    StorelessUnivariateStatistic copy();
+
+}