provided.client.model.task

Class Pi2

java.lang.Object

provided.client.model.task.Pi2

All Implemented Interfaces:

java.io.Serializable, ITask<java.math.BigDecimal>

public class Pi2
extends java.lang.Object
implements ITask<java.math.BigDecimal>

Task to compute PI to a given number of digits

Author:

swong

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private int	digits digits of precision after the decimal point
static ITaskFactory<java.math.BigDecimal>	FACTORY An ITaskFactory for this task
private static java.math.BigDecimal	FOUR constants used in pi computation
private static int	roundingMode rounding mode to use during pi computation
private static long	serialVersionUID SerialversionUID for well-defined serialization.
private ILocalTaskViewAdapter	taskView Adapter to the local view.

Constructor Summary

Constructors

Constructor and Description
Pi2(int digits) Construct a task to calculate pi to the specified precision.

Method Summary

Modifier and Type	Method and Description
private java.math.BigDecimal	arctan(int inverseX, int scale) Compute the value, in radians, of the arctangent of the inverse of the supplied integer to the specified number of digits after the decimal point.
private java.math.BigDecimal	computePi(int digits) Compute the value of pi to the specified number of digits after the decimal point.
java.math.BigDecimal	execute() Calculate pi.
ITaskResultFormatter<java.math.BigDecimal>	getFormatter() Return a a formatter that makes a string of the form: "Pi = [result] ([digits] places)" Notice how the "digits" value is not part of the result, but that the formatter can use it anyway because the formatter is closing over the whole task.
private void	readObject(java.io.ObjectInputStream stream) Reinitializes transient fields upon deserialization.
void	setTaskViewAdapter(ILocalTaskViewAdapter viewAdapter) Sets the task view adapter to a new value.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

SerialversionUID for well-defined serialization.

See Also:

Constant Field Values

taskView

private transient ILocalTaskViewAdapter taskView

Adapter to the local view. Marked "transient" so that it is not serialized and instead is reattached at the destination (the server).

FOUR

private static final java.math.BigDecimal FOUR

constants used in pi computation

roundingMode

private static final int roundingMode

rounding mode to use during pi computation

See Also:

Constant Field Values

digits

private final int digits

digits of precision after the decimal point

FACTORY

public static final ITaskFactory<java.math.BigDecimal> FACTORY

An ITaskFactory for this task

Constructor Detail

Pi2

public Pi2(int digits)

Construct a task to calculate pi to the specified precision.

Parameters:

digits - the number of digits to calculate PI to

Method Detail

execute

public java.math.BigDecimal execute()

Calculate pi.

Specified by:

execute in interface ITask<java.math.BigDecimal>

Returns:

a BigDecimal object with the value of Pi

computePi

private java.math.BigDecimal computePi(int digits)

Compute the value of pi to the specified number of digits after the decimal point. The value is computed using Machin's formula: pi/4 = 4*arctan(1/5) - arctan(1/239) and a power series expansion of arctan(x) to sufficient precision.

Parameters:

digits - the number of digits of precision desired

Returns:

a BigDecimal object with the value of Pi

arctan

private java.math.BigDecimal arctan(int inverseX,
                                    int scale)

Compute the value, in radians, of the arctangent of the inverse of the supplied integer to the specified number of digits after the decimal point. The value is computed using the power series expansion for the arc tangent: arctan(x) = x - (x^3)/3 + (x^5)/5 - (x^7)/7 + (x^9)/9 ...

Parameters:

inverseX - integer whose inverse will be used to calculate the arctan

scale - number of digits of precision desired

Returns:

the arctan value

readObject

private void readObject(java.io.ObjectInputStream stream)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException

Reinitializes transient fields upon deserialization. See the Serializable marker interface docs. taskView is set to a default value for now (ILocalTaskViewAdapter.DEFAULT_ADAPTER).

Parameters:

stream - The object stream with the serialized data

Throws:

java.io.IOException - if the input stream cannot be read correctly

java.lang.ClassNotFoundException - if the class file associated with the input stream cannot be located.

setTaskViewAdapter

public void setTaskViewAdapter(ILocalTaskViewAdapter viewAdapter)

Sets the task view adapter to a new value. Used by the server to attach the task to its view.

Specified by:

setTaskViewAdapter in interface ITask<java.math.BigDecimal>

Parameters:

viewAdapter - an adapter to the view.

getFormatter

public ITaskResultFormatter<java.math.BigDecimal> getFormatter()

Return a a formatter that makes a string of the form: "Pi = [result] ([digits] places)" Notice how the "digits" value is not part of the result, but that the formatter can use it anyway because the formatter is closing over the whole task.

Specified by:

getFormatter in interface ITask<java.math.BigDecimal>

Returns:

A formatter customized for this task object.