com.klg.jclass.util.formulae
Class StdDeviation

java.lang.Object
  |
  +--com.klg.jclass.util.formulae.Operation
        |
        +--com.klg.jclass.util.formulae.StdDeviation

All Implemented Interfaces:

Cloneable, Expression

public class StdDeviation

extends Operation

This is a concrete implementation for the Standard Deviation operation. We implement the "unbiased" estimator version of standard deviation, since that is what's commonly understood by "Standard Deviation." In essence, the implementation is: sd = root( (sum(1 to N)(element - average)^2) / (n - 1))

Field Summary

Fields inherited from class com.klg.jclass.util.formulae.Operation

leftOperand, rightOperand

Constructor Summary

StdDeviation(com.klg.jclass.util.formulae.Expression operand)
The standard deviation of the given list of elements

StdDeviation(com.klg.jclass.util.formulae.Expression operand1, com.klg.jclass.util.formulae.Expression operand2)
Standard Deviation of a pair of operands

Method Summary

com.klg.jclass.util.formulae.Result

evaluate() Return the result of computing the population standard deviation over the operands (all members have equal probability)

Methods inherited from class com.klg.jclass.util.formulae.Operation

clone

Methods inherited from class java.lang.Object

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

Constructor Detail

StdDeviation

public StdDeviation(com.klg.jclass.util.formulae.Expression operand)

The standard deviation of the given list of elements

StdDeviation

public StdDeviation(com.klg.jclass.util.formulae.Expression operand1,
                    com.klg.jclass.util.formulae.Expression operand2)

Standard Deviation of a pair of operands

Method Detail

evaluate

public com.klg.jclass.util.formulae.Result evaluate()

Return the result of computing the population standard deviation over the operands (all members have equal probability)

Specified by:

evaluate in interface Expression

Specified by:

evaluate in class Operation

Returns:

The standard deviation of all the operands