com.pervasive.datarush.operators.assertion

Class UlpDistanceBound

java.lang.Object

com.pervasive.datarush.operators.assertion.UlpDistanceBound

All Implemented Interfaces:

FloatingPointTolerance

public class UlpDistanceBound
extends Object
implements FloatingPointTolerance

Checks equivalence based on the distance between two floating point numbers in units of least precision (ULP). Two values are considered equal if this error is less than a fixed bound.

The ULP is based on the representation of the values rather than the values itself. As errors in single- and double-precision floating point arithmetic stem from the inability to precisely represent values, measuring the distance in ULPs can provide a bound which is more consistent in behavior, regardless of the the scale of the the values.

As the ULP is based on the IEEE 754 specification for floating point, this tolerance is not supported for BigDecimal.

Field Summary

Fields inherited from interface com.pervasive.datarush.operators.assertion.FloatingPointTolerance

EXACT

Constructor Summary

Constructors

Constructor and Description
UlpDistanceBound(int maxUlps) Define a fixed bound on the distance between two floating point values, measured in ULPs.

Method Summary

Modifier and Type	Method and Description
int	getMaxUlps() Gets the maximum number of ULPs allowed between two values.
boolean	isWithinTolerance(BigDecimal value1, BigDecimal value2) Indicates whether the specified values are equal under the tolerance.
boolean	isWithinTolerance(double value1, double value2) Indicates whether the specified values are equal under the tolerance.
boolean	isWithinTolerance(float value1, float value2) Indicates whether the specified values are equal under the tolerance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UlpDistanceBound

public UlpDistanceBound(int maxUlps)

Define a fixed bound on the distance between two floating point values, measured in ULPs.

Parameters:

maxUlps - the fixed bound on the distance, in ULPS

Throws:

com.pervasive.datarush.graphs.physical.InvalidPropertyValueException - if epsilon is negative.

Method Detail

isWithinTolerance

public boolean isWithinTolerance(float value1,
                                 float value2)

Description copied from interface: FloatingPointTolerance

Indicates whether the specified values are equal under the tolerance.

Specified by:

isWithinTolerance in interface FloatingPointTolerance

Parameters:

value1 - the first value to compare

value2 - the second value to compare

Returns:

true if the two values lie with the error bounds, otherwise false

isWithinTolerance

public boolean isWithinTolerance(double value1,
                                 double value2)

Description copied from interface: FloatingPointTolerance

Indicates whether the specified values are equal under the tolerance.

Specified by:

isWithinTolerance in interface FloatingPointTolerance

Parameters:

value1 - the first value to compare

value2 - the second value to compare

Returns:

true if the two values lie with the error bounds, otherwise false

isWithinTolerance

public boolean isWithinTolerance(BigDecimal value1,
                                 BigDecimal value2)

Indicates whether the specified values are equal under the tolerance.

ULP based tolerance is not supported for BigDecimal values.

Specified by:

isWithinTolerance in interface FloatingPointTolerance

Parameters:

value1 - the first value to compare

value2 - the second value to compare

Returns:

true if the two values lie with the error bounds, otherwise false

getMaxUlps

public int getMaxUlps()

Gets the maximum number of ULPs allowed between two values.

Returns:

the ULP distance bound