summaryrefslogtreecommitdiff
path: root/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java
diff options
context:
space:
mode:
Diffstat (limited to 'src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java')
-rw-r--r--src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java91
1 files changed, 91 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java b/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java
new file mode 100644
index 0000000..ec38c4d
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java
@@ -0,0 +1,91 @@
+/*
+ * 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.random;
+
+import org.apache.commons.math3.exception.DimensionMismatchException;
+
+import java.util.Arrays;
+
+/**
+ * A {@link RandomVectorGenerator} that generates vectors with uncorrelated components. Components
+ * of generated vectors follow (independent) Gaussian distributions, with parameters supplied in the
+ * constructor.
+ *
+ * @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.
+ *
+ * @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
+ *
+ * @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;
+ }
+}