org.lsmp.djep.xjep.function

Class Trapezium

java.lang.Object

org.nfunk.jep.function.PostfixMathCommand

org.lsmp.djep.xjep.function.SumType

org.lsmp.djep.xjep.function.Trapezium

All Implemented Interfaces:

CallbackEvaluationI, PostfixMathCommandI

Direct Known Subclasses:

Simpson

public class Trapezium
extends SumType

The trapezium rule for approximation to a definite integral. h * (y0 + yn + 2(y1+y2+...+y_(n-1)) /2 where h = (xn-x0)/n, yi = f(xi) Trapezium(x^2,x,0,10,0.5) finds an approximation for int(x^2) where x runs from 0 to 10 in steps of h=0.5.

Author:

Rich Morris Created on 10-Sept-2004

Field Summary

Fields inherited from class org.lsmp.djep.xjep.function.SumType

name

Fields inherited from class org.nfunk.jep.function.PostfixMathCommand

curNumberOfParameters, numberOfParameters

Constructor Summary

Constructors

Constructor and Description
Trapezium()
Trapezium(String name)

Method Summary

Modifier and Type	Method and Description
Object	evaluate(Node node, Variable var, double min, double max, double inc, EvaluatorI pv) Evaluates the node by repeatibly setting the value of the variable from min to max, and calculating the value of the first argument.
Object	evaluate(Object[] elements) Evaluates the function given the set of y values.

Methods inherited from class org.lsmp.djep.xjep.function.SumType

checkNumberOfParameters, evaluate, run

Methods inherited from class org.nfunk.jep.function.PostfixMathCommand

checkStack, getNumberOfParameters, setCurNumberOfParameters

Methods inherited from class java.lang.Object

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

Constructor Detail

Trapezium

public Trapezium()

Trapezium

public Trapezium(String name)

Method Detail

evaluate

public Object evaluate(Object[] elements)
                throws ParseException

Description copied from class: SumType

Evaluates the function given the set of y values. For example for Sum(x^2,x,1,5) the function will be passed the array [1,4,9,16,25].

Specified by:

evaluate in class SumType

Parameters:

elements - the y values

Returns:

the result of the function

Throws:

ParseException

evaluate

public Object evaluate(Node node,
                       Variable var,
                       double min,
                       double max,
                       double inc,
                       EvaluatorI pv)
                throws ParseException

Description copied from class: SumType

Evaluates the node by repeatibly setting the value of the variable from min to max, and calculating the value of the first argument. Sub classes generally do not need to implement this method as SumType.evaluate(Object[]) is more useful. If they do they should follow the pattern used here.

Overrides:

evaluate in class SumType

Returns:

the result of evaluation

Throws:

ParseException