[New] added MathHelper for precision assertions

src/main/java/ch/eitchnet/utils/helper/MathHelper.java

@@ -0,0 +1,121 @@
+/*
+ * Created on 05.01.2004
+ */
+
+/*
+ * Copyright (c) 2006 - 2011 Apixxo AG Hauptgasse 25 4600
+ * Olten
+ * 
+ * All rights reserved.
+ * 
+ */
+
+package ch.eitchnet.utils.helper;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+/**
+ * A helper class that contains mathematical computations that can be used throughout.
+ * 
+ * @author msmock, gattom
+ */
+public class MathHelper {
+
+	public static final double PRECISION = 1.0E08;
+	public static final int PRECISION_DIGITS = 3;
+
+	/**
+	 * Check if the two values are equal with respect to the precision
+	 * 
+	 * @param firstValue
+	 *            the first value to compare
+	 * @param secondValue
+	 *            the second value to compare to
+	 * @return boolean True, if the two values are equal under the set precision. Fales, otherwise.
+	 */
+	public static boolean isEqualPrecision(double firstValue, double secondValue) {
+
+		return (java.lang.Math.abs(firstValue - secondValue) < (1.0d / PRECISION));
+	}
+
+	/**
+	 * Comparison between the two values. Given the precision, this function determines if the given value is smaller
+	 * than the given bound.
+	 * <p>
+	 * Note: this implementation tests if the value < bound, and if this is not so, checks if the values are equal under
+	 * the precision. Thus, it's efficient whenever the value is expected to be smaller than the bound.
+	 * 
+	 * @param value
+	 *            The value to check
+	 * @param bound
+	 *            The bound given
+	 * @return true, if value < bound under the given precision. False, otherwise.
+	 */
+	public static boolean isSmallerEqualPrecision(double value, double bound) {
+		if (value < bound)
+			return true;
+		return isEqualPrecision(value, bound);
+	}
+
+	/**
+	 * Comparison between two values. Given the precision, this function determines if the given value is greater than
+	 * the given bound.
+	 * <p>
+	 * Note: This implementation tests if value > bound and, if it is so, if equality does NOT hold. Thus, it is
+	 * efficient whenever the value is not expected to be greater than the bound.
+	 * 
+	 * @param value
+	 *            The value to check
+	 * @param bound
+	 *            The bound given.
+	 * @return true, if value > bound and the values do not test equal under precision. False, otherwise.
+	 */
+	public static boolean isGreaterPrecision(double value, double bound) {
+		return (value > bound) && !isEqualPrecision(value, bound);
+	}
+
+	/**
+	 * <p>
+	 * Rounds the given double value to the number of decimals
+	 * </p>
+	 * 
+	 * <p>
+	 * <b>Warning:</b> Do not use the returned value for further calculations. Always finish calculates and use one of
+	 * the following methods:
+	 * <ul>
+	 * <li>{@link #isEqualPrecision(double, double)},</li>
+	 * <li>{@link #isGreaterPrecision(double, double)} or</li>
+	 * <li>{@link #isSmallerEqualPrecision(double, double)}</li>
+	 * </ul>
+	 * to test on equality or greater than/ smaller than
+	 * </p>
+	 * 
+	 * @param value
+	 *            the double value to round
+	 * @param decimals
+	 *            number of decimals
+	 * 
+	 * @return the rounded number
+	 */
+	public static double toPrecision(double value, int decimals) {
+		if (value == 0.0)
+			return 0.0;
+		if (Double.isNaN(value))
+			return Double.NaN;
+		if (value == Double.NEGATIVE_INFINITY)
+			return Double.NEGATIVE_INFINITY;
+		if (value == Double.POSITIVE_INFINITY)
+			return Double.POSITIVE_INFINITY;
+		return new BigDecimal(value).setScale(decimals, RoundingMode.HALF_EVEN).doubleValue();
+	}
+
+	/**
+	 * Returns the value with the precision where precision is set to {@link #PRECISION_DIGITS}
+	 * 
+	 * @see #toPrecision(double, int)
+	 */
+	public static double toPrecision(double value) {
+		return toPrecision(value, PRECISION_DIGITS);
+	}
+}