Я написал класс, который проверяет равенство, меньше и больше, чем с двумя двойными в Java. В моем общем случае сравнивается цена, которая может иметь точность в полтора процента. 59,005 по сравнению с 59,395. Является ли эпсилон, который я выбрал адекватным для этих случаев?
private final static double EPSILON = 0.00001;
/**
* Returns true if two doubles are considered equal. Tests if the absolute
* difference between two doubles has a difference less then .00001. This
* should be fine when comparing prices, because prices have a precision of
* .001.
*
* @param a double to compare.
* @param b double to compare.
* @return true true if two doubles are considered equal.
*/
public static boolean equals(double a, double b){
return a == b ? true : Math.abs(a - b) < EPSILON;
}
/**
* Returns true if two doubles are considered equal. Tests if the absolute
* difference between the two doubles has a difference less then a given
* double (epsilon). Determining the given epsilon is highly dependant on the
* precision of the doubles that are being compared.
*
* @param a double to compare.
* @param b double to compare
* @param epsilon double which is compared to the absolute difference of two
* doubles to determine if they are equal.
* @return true if a is considered equal to b.
*/
public static boolean equals(double a, double b, double epsilon){
return a == b ? true : Math.abs(a - b) < epsilon;
}
/**
* Returns true if the first double is considered greater than the second
* double. Test if the difference of first minus second is greater then
* .00001. This should be fine when comparing prices, because prices have a
* precision of .001.
*
* @param a first double
* @param b second double
* @return true if the first double is considered greater than the second
* double
*/
public static boolean greaterThan(double a, double b){
return greaterThan(a, b, EPSILON);
}
/**
* Returns true if the first double is considered greater than the second
* double. Test if the difference of first minus second is greater then
* a given double (epsilon). Determining the given epsilon is highly
* dependant on the precision of the doubles that are being compared.
*
* @param a first double
* @param b second double
* @return true if the first double is considered greater than the second
* double
*/
public static boolean greaterThan(double a, double b, double epsilon){
return a - b > epsilon;
}
/**
* Returns true if the first double is considered less than the second
* double. Test if the difference of second minus first is greater then
* .00001. This should be fine when comparing prices, because prices have a
* precision of .001.
*
* @param a first double
* @param b second double
* @return true if the first double is considered less than the second
* double
*/
public static boolean lessThan(double a, double b){
return lessThan(a, b, EPSILON);
}
/**
* Returns true if the first double is considered less than the second
* double. Test if the difference of second minus first is greater then
* a given double (epsilon). Determining the given epsilon is highly
* dependant on the precision of the doubles that are being compared.
*
* @param a first double
* @param b second double
* @return true if the first double is considered less than the second
* double
*/
public static boolean lessThan(double a, double b, double epsilon){
return b - a > epsilon;
}