com.softicar.platform.common.math.rounding.Rounding Maven / Gradle / Ivy
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package com.softicar.platform.common.math.rounding;
import java.math.BigDecimal;
/**
* Provides rounding and comparison methods for floating point number.
*
* @author Boris Schaa
* @author Thees Koester
* @author Oliver Richers
*/
public class Rounding {
/**
* Compares the given values using the specified decimal precision.
*
* Please read the Javadoc of {@link Rounding#round(double, int)} regarding
* floating point types.
*
* @param a
* the first value
* @param b
* the second value
* @param precision
* the number of decimal places to use for comparison
* @return true if the given values can be considered as equal with the
* given precision
*/
public static boolean equal(double a, double b, int precision) {
return Math.abs(a - b) < 1.0 / Math.pow(10, precision);
}
/**
* Rounds the given floating point value to the specified decimal precision.
*
* Please note, that there are a lot of pitfalls when dealing with decimal
* numbers and floating point types like double. For example,
* Rounding.round(0.009, 2) == 0.01 may be true but it may
* also be false. If you really need to deal with decimal numbers
* then you should consider using {@link BigDecimal} instead of floating
* point types. Especially, when dealing with financial data, correctness
* might be more important that speed.
*
* @param value
* the floating point value to round
* @param precision
* the number of decimal places to round to
* @return the given value rounded with the given precision
*/
public static double round(double value, int precision) {
double power = Math.pow(10, precision);
return Math.round(power * value) / power;
}
}