com.jstatcom.parser
Class CalcFunctions

java.lang.Object
  com.jstatcom.parser.CalcFunctions

public abstract class CalcFunctions
extends java.lang.Object

Enumeration of all functions that are used by CalcEngine. The defined functions objects override execute(int argNum, Stack argStack) to provide the respective functionality. All functions get their arguments from a stack and put the results back on the stack after successful computation.

Author:

Markus Kraetzig

Field Summary

static CalcFunctions	COS cos(a), computes cosinus function for all elements of an array.
static CalcFunctions	FRACDIFF fracdiff(a, d), fractional differences of a.
static CalcFunctions	LAGN lagn(a,b), lags the array by b elements and fills the resulting free slots with Double.NaN.
static CalcFunctions	LOG log(a), computes natural logarithm for all elements of an array.
static CalcFunctions	MAX max(a,b), returns an array with the maximum elements of a and b for each row.
static CalcFunctions	MEANC meanc(a), computes the mean of all elements in an array.
static CalcFunctions	MIN min(a,b), returns an array with the minimum elements of a and b for each row.
static CalcFunctions	ONES ones(a), creates an array of ones with dimension (a x 1).
static CalcFunctions	REVERSE reverse(a), reverses the order of an array, starting from observation T to 1.
static CalcFunctions	RNDN rndn(a), creates an array of a random numbers between 0 and 1.
static CalcFunctions	ROWS rows(a), gets the rows of an array.
static CalcFunctions	SIN sin(a), computes sinus function for all elements of an array.
static CalcFunctions	SQRT sqrt(a), computes square root for all elements of an array.
static CalcFunctions	STAND stand(a), creates a normalized version if the array by subtracting the mean and dividing by the standard deviation.
static CalcFunctions	STDC stdc(a), computes the standard deviation of all elements in an array.
static CalcFunctions	SUMC sumc(a), computes the sum of all elements in an array.
static CalcFunctions	TAN tan(a), computes tangens function for all elements of an array.
static CalcFunctions	TREND trend(a), creates an array of numbers incremented by 1 with dimension (a x 1), starting from 1.

Method Summary

static void	callFunctionForName(java.lang.String functionName, int argNum, java.util.Stack<double[]> argStack) Executes a function specified with a name.
boolean	equals(java.lang.Object o) Override prevention method to enforce a.equals(b) if and only if a==b.
abstract void	execute(int argNum, java.util.Stack<double[]> argStack) This defines the operation that is actually carried out by the function.
static int	getLength(double[] aa, double[] bb) Computes the correct length when 2 array are combined.
int	hashCode() Override prevention method invokes super method.
java.lang.String	toString() Returns the name of the runtype, do not use for comparisons.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

FRACDIFF

public static final CalcFunctions FRACDIFF

fracdiff(a, d), fractional differences of a.

SIN

public static final CalcFunctions SIN

sin(a), computes sinus function for all elements of an array.

COS

public static final CalcFunctions COS

cos(a), computes cosinus function for all elements of an array.

TAN

public static final CalcFunctions TAN

tan(a), computes tangens function for all elements of an array.

SQRT

public static final CalcFunctions SQRT

sqrt(a), computes square root for all elements of an array.

LOG

public static final CalcFunctions LOG

log(a), computes natural logarithm for all elements of an array. Fails, if the array contains values smaller or equal to zero.

LAGN

public static final CalcFunctions LAGN

lagn(a,b), lags the array by b elements and fills the resulting free slots with Double.NaN. Lagging means, that every element i is replaced by the element in i-b. The argument b can also be negative, which would result in a forward shift.

ROWS

public static final CalcFunctions ROWS

rows(a), gets the rows of an array.

ONES

public static final CalcFunctions ONES

ones(a), creates an array of ones with dimension (a x 1).

TREND

public static final CalcFunctions TREND

trend(a), creates an array of numbers incremented by 1 with dimension (a x 1), starting from 1.

RNDN

public static final CalcFunctions RNDN

rndn(a), creates an array of a random numbers between 0 and 1.

SUMC

public static final CalcFunctions SUMC

sumc(a), computes the sum of all elements in an array.

MEANC

public static final CalcFunctions MEANC

meanc(a), computes the mean of all elements in an array.

STDC

public static final CalcFunctions STDC

stdc(a), computes the standard deviation of all elements in an array.

STAND

public static final CalcFunctions STAND

stand(a), creates a normalized version if the array by subtracting the mean and dividing by the standard deviation.

REVERSE

public static final CalcFunctions REVERSE

reverse(a), reverses the order of an array, starting from observation T to 1.

MIN

public static final CalcFunctions MIN

min(a,b), returns an array with the minimum elements of a and b for each row.

MAX

public static final CalcFunctions MAX

max(a,b), returns an array with the maximum elements of a and b for each row.

Method Detail

callFunctionForName

public static void callFunctionForName(java.lang.String functionName,
                                       int argNum,
                                       java.util.Stack<double[]> argStack)
                                throws java.lang.IllegalArgumentException

Executes a function specified with a name.

Parameters:

functionName - a case insensitive String with the name of the function to call

argNum - the number of arguments to the function

argStack - the current Stack to store the input as well as the result

Throws:

java.lang.IllegalArgumentException - in case the function does not exist or the arguments are wrong

equals

public final boolean equals(java.lang.Object o)

Override prevention method to enforce a.equals(b) if and only if a==b.

Overrides:

equals in class java.lang.Object

Parameters:

o - object to compare with

Returns:

true if equal, false otherwise

execute

public abstract void execute(int argNum,
                             java.util.Stack<double[]> argStack)

This defines the operation that is actually carried out by the function. The method must be overridden if you define a new function. Input parameters as well as results are contained in the argStack.

Parameters:

argNum - the number of arguments to the function

argStack - the current Stack to store the input as well as the result

getLength

public static int getLength(double[] aa,
                            double[] bb)
                     throws java.lang.IllegalArgumentException

Computes the correct length when 2 array are combined.

Parameters:

aa - double array

bb - double array

Returns:

the length for the result array

Throws:

ParseException - if (aa.length != bb.length) && (aa.length != 1) && (bb.length != 1)

java.lang.IllegalArgumentException

hashCode

public final int hashCode()

Override prevention method invokes super method.

Overrides:

hashCode in class java.lang.Object

Returns:

hash code

toString

public final java.lang.String toString()

Returns the name of the runtype, do not use for comparisons.

Overrides:

toString in class java.lang.Object