com.singularsys.jep.functions

Class Logarithm

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.functions.UnaryFunction

com.singularsys.jep.functions.Logarithm

All Implemented Interfaces:

PostfixMathCommandI, RealUnaryFunction, java.io.Serializable

public class Logarithm
extends UnaryFunction
implements RealUnaryFunction

Log base 10. By default negative arguments will return a complex result

log(|x|) + pi i

if the strict flag is set in the constructor

version 3.4: Speedup by using static final fields.

version 3.4: Change to use Java 5 Math.log10() method.

version 3.5: For negative arguments log10(-x) =log10(x) + i pi log10(e) as 10^(log10(x) + i log10(e)) = x * e^(i pi) = -x. For complex arguments(x+i y) = r e^(i th) log10(r e^(i th)) = log10(r) + i th log10(e) as 10^(log10(r) + i th log10(e)) = r * e^(i th).

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	strict

Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand

curNumberOfParameters, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor and Description
Logarithm() Standard constructor, returns complex results for negative arguments
Logarithm(boolean strict) Constructor with control for behaviour for complex results

Method Summary

Modifier and Type	Method and Description
java.lang.Object	eval(java.lang.Object arg)
double	evaluate(double val)
java.lang.Object	log(java.lang.Object param)

Methods inherited from class com.singularsys.jep.functions.UnaryFunction

run

Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand

asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, checkNumberOfParameters, getName, getNumberOfParameters, setCurNumberOfParameters, setName, toString, toString

Methods inherited from class java.lang.Object

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

Field Detail

strict

protected final boolean strict

Constructor Detail

Logarithm

public Logarithm(boolean strict)

Constructor with control for behaviour for complex results

Parameters:

strict - if true negative real arguments return NaN, otherwise complex results are returned

Logarithm

public Logarithm()

Standard constructor, returns complex results for negative arguments

Method Detail

eval

public java.lang.Object eval(java.lang.Object arg)
                      throws EvaluationException

Specified by:

eval in class UnaryFunction

Throws:

EvaluationException

log

public java.lang.Object log(java.lang.Object param)
                     throws EvaluationException

Throws:

EvaluationException

evaluate

public double evaluate(double val)

Specified by:

evaluate in interface RealUnaryFunction