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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.math.random;
+
+import java.util.Arrays;
+
+import org.apache.commons.math.exception.DimensionMismatchException;
+
+/**
+ * A {@link RandomVectorGenerator} that generates vectors with uncorrelated
+ * components. Components of generated vectors follow (independent) Gaussian
+ * distributions, with parameters supplied in the constructor.
+ *
+ * @version $Revision: 962515 $ $Date: 2010-07-09 15:15:28 +0200 (ven. 09 juil. 2010) $
+ * @since 1.2
+ */
+
+public class UncorrelatedRandomVectorGenerator
+ implements RandomVectorGenerator {
+
+ /** Underlying scalar generator. */
+ private final NormalizedRandomGenerator generator;
+
+ /** Mean vector. */
+ private final double[] mean;
+
+ /** Standard deviation vector. */
+ private final double[] standardDeviation;
+
+ /** Simple constructor.
+ * <p>Build an uncorrelated random vector generator from
+ * its mean and standard deviation vectors.</p>
+ * @param mean expected mean values for each component
+ * @param standardDeviation standard deviation for each component
+ * @param generator underlying generator for uncorrelated normalized
+ * components
+ */
+ public UncorrelatedRandomVectorGenerator(double[] mean,
+ double[] standardDeviation,
+ NormalizedRandomGenerator generator) {
+ if (mean.length != standardDeviation.length) {
+ throw new DimensionMismatchException(mean.length, standardDeviation.length);
+ }
+ this.mean = mean.clone();
+ this.standardDeviation = standardDeviation.clone();
+ this.generator = generator;
+ }
+
+ /** Simple constructor.
+ * <p>Build a null mean random and unit standard deviation
+ * uncorrelated vector generator</p>
+ * @param dimension dimension of the vectors to generate
+ * @param generator underlying generator for uncorrelated normalized
+ * components
+ */
+ public UncorrelatedRandomVectorGenerator(int dimension,
+ NormalizedRandomGenerator generator) {
+ mean = new double[dimension];
+ standardDeviation = new double[dimension];
+ Arrays.fill(standardDeviation, 1.0);
+ this.generator = generator;
+ }
+
+ /** Generate an uncorrelated random vector.
+ * @return a random vector as a newly built array of double
+ */
+ public double[] nextVector() {
+
+ double[] random = new double[mean.length];
+ for (int i = 0; i < random.length; ++i) {
+ random[i] = mean[i] + standardDeviation[i] * generator.nextNormalizedDouble();
+ }
+
+ return random;
+
+ }
+
+}