maspack.function

Class LinearFunctionNx1

java.lang.Object

maspack.function.Diff1FunctionNx1Base

maspack.function.LinearFunctionNx1

All Implemented Interfaces:

java.lang.Cloneable, Diff1FunctionNx1, FunctionNx1, Clonable, Scannable

public class LinearFunctionNx1
extends Diff1FunctionNx1Base

Implements a linear function of n arguments defined by a set of n+1 coefficients c:

 
 y = sum c[i]*in[i] + c[n]

Constructor Summary

Constructors

Constructor and Description
LinearFunctionNx1() Creates an empty LinearFunctionNx1
LinearFunctionNx1(double[] coefs) Creates a new LinearFunctionNx1 with the specified coefficients.
LinearFunctionNx1(double m, double b) Creates a new LinearFunctionNx1 with a single argument defined by
LinearFunctionNx1(VectorNd coefs) Creates a new LinearFunctionNx1 with the specified coefficients.

Method Summary

Modifier and Type	Method and Description
LinearFunctionNx1	clone()
boolean	equals(LinearFunctionNx1 fxn) Returns true if fxn is equal to this function.
double	eval(VectorNd in) Evaluates this function for the specified inputs.
double	eval(VectorNd deriv, VectorNd in) Evaluates this function for the specified inputs.
double[]	getCoefficients() Returns the coefficients of this function.
int	inputSize() Queries the number of inputs expected by this function.
void	scan(ReaderTokenizer rtok, java.lang.Object ref) Scans this element from a ReaderTokenizer.
void	setCoefficients(double[] coefs) Sets the coefficients of this function.
void	setCoefficients(double m, double b) Sets this function to one with a single argument defined by
void	write(java.io.PrintWriter pw, NumberFormat fmt, java.lang.Object ref) Writes a text description of this element to a PrintWriter.

Methods inherited from class maspack.function.Diff1FunctionNx1Base

isWritable

Methods inherited from class java.lang.Object

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

Methods inherited from interface maspack.function.Diff1FunctionNx1

evalDeriv

Constructor Detail

LinearFunctionNx1

public LinearFunctionNx1()

Creates an empty LinearFunctionNx1

LinearFunctionNx1

public LinearFunctionNx1(double[] coefs)

Creates a new LinearFunctionNx1 with the specified coefficients.

Parameters:

coefs - function coefficents (will be copied)

LinearFunctionNx1

public LinearFunctionNx1(VectorNd coefs)

Creates a new LinearFunctionNx1 with the specified coefficients.

Parameters:

coefs - function coefficents (will be copied)

LinearFunctionNx1

public LinearFunctionNx1(double m,
                         double b)

Creates a new LinearFunctionNx1 with a single argument defined by

 y = m*in[0] + b
 

Parameters:

m - slope of the function

b - intercept of the function

Method Detail

setCoefficients

public void setCoefficients(double m,
                            double b)

Sets this function to one with a single argument defined by

 y = m*in[0] + b
 

Parameters:

m - slope of the function

b - intercept of the function

setCoefficients

public void setCoefficients(double[] coefs)

Sets the coefficients of this function.

Parameters:

coefs - function coefficents (will be copied)

getCoefficients

public double[] getCoefficients()

Returns the coefficients of this function.

Returns:

function coefficents (should not be modified)

inputSize

public int inputSize()

Queries the number of inputs expected by this function.

Returns:

number of expected inputs

eval

public double eval(VectorNd in)

Evaluates this function for the specified inputs. The input vector size must the value returned by FunctionNx1.inputSize().

Specified by:

eval in interface FunctionNx1

Specified by:

eval in class Diff1FunctionNx1Base

Returns:

function output value

eval

public double eval(VectorNd deriv,
                   VectorNd in)

Evaluates this function for the specified inputs. If deriv is not null, the derivative is also computed and returned in this argument. The input vector size should equal the value returned by FunctionNx1.inputSize(). If present, deriv will be resized, if necessary, to FunctionNx1.inputSize().

Specified by:

eval in interface Diff1FunctionNx1

Specified by:

eval in class Diff1FunctionNx1Base

Parameters:

deriv - if not null, returns the derivative values

in - function input values

Returns:

function output value

scan

public void scan(ReaderTokenizer rtok,
                 java.lang.Object ref)
          throws java.io.IOException

Scans this element from a ReaderTokenizer. The expected text format is assumed to be compatible with that produced by write.

Specified by:

scan in interface Scannable

Overrides:

scan in class Diff1FunctionNx1Base

Parameters:

rtok - Tokenizer from which to scan the element

ref - optional reference object which can be used for resolving references to other objects

Throws:

java.io.IOException - if an I/O or formatting error occured

write

public void write(java.io.PrintWriter pw,
                  NumberFormat fmt,
                  java.lang.Object ref)
           throws java.io.IOException

Writes a text description of this element to a PrintWriter. The text description should be compatable with scan and complete enough to allow full reconstruction of the element.

Specified by:

write in interface Scannable

Overrides:

write in class Diff1FunctionNx1Base

Parameters:

pw - stream for writing the element

fmt - numeric formating information

ref - optional reference object which can be used for producing references to other objects

Throws:

java.io.IOException - if an I/O error occured

equals

public boolean equals(LinearFunctionNx1 fxn)

Returns true if fxn is equal to this function.

clone

public LinearFunctionNx1 clone()

Specified by:

clone in interface Clonable

Overrides:

clone in class Diff1FunctionNx1Base