Represents a function computing a ratio of two values. More...

Inheritance diagram for umontreal.ssj.util.RatioFunction:

Public Member Functions
	RatioFunction ()
	Constructs a new ratio function.
	RatioFunction (double zeroOverZero)
	Constructs a new ratio function that returns zeroOverZero for the special case of \(0/0\).
double	getZeroOverZeroValue ()
	Returns the value returned by evaluate in the case where the \(0/0\) function is calculated.
void	setZeroOverZeroValue (double zeroOverZero)
	Sets the value returned by evaluate for the undefined function \(0/0\) to zeroOverZero.
int	getDimension ()
	Returns \(d\), the dimension of the function computed by this implementation.
double	evaluate (double... x)
	Computes the function \(g(\mathbf{x})\) for the vector x.
double	evaluateGradient (int i, double... x)
	Computes \(\partial g(\mathbf{x})/\partial x_i\), the derivative of \(g(\mathbf{x})\) with respect to \(x_i\).

Detailed Description

Represents a function computing a ratio of two values.

Definition at line 32 of file RatioFunction.java.

Constructor & Destructor Documentation

◆ RatioFunction() [1/2]

umontreal.ssj.util.RatioFunction.RatioFunction ( )

Constructs a new ratio function.

Definition at line 38 of file RatioFunction.java.

◆ RatioFunction() [2/2]

umontreal.ssj.util.RatioFunction.RatioFunction ( double zeroOverZero )

Constructs a new ratio function that returns zeroOverZero for the special case of \(0/0\).

See the getZeroOverZeroValue method for more information. The default value of zeroOverZero is Double.NaN.

Parameters

zeroOverZero the value for \(0/0\).

Definition at line 48 of file RatioFunction.java.

Member Function Documentation

◆ evaluate()

double umontreal.ssj.util.RatioFunction.evaluate ( double... x )

Computes the function \(g(\mathbf{x})\) for the vector x.

The length of the given array must correspond to the dimension of this function. The method must compute and return the result of the function without modifying the elements in x since the array can be reused for further computation.

Parameters

x	a vector \(\mathbf{x}\).

Returns: the value of \(g(\mathbf{x})\).

Exceptions

NullPointerException	if `x` is `null`.
IllegalArgumentException	if `x.length` does not correspond to the dimension of this function.

Implements umontreal.ssj.util.MultivariateFunction.

Definition at line 89 of file RatioFunction.java.

◆ evaluateGradient()

double umontreal.ssj.util.RatioFunction.evaluateGradient	(	int	i,
		double...	x )

Computes \(\partial g(\mathbf{x})/\partial x_i\), the derivative of \(g(\mathbf{x})\) with respect to \(x_i\).

The length of the given array must correspond to the dimension of this function. The method must compute and return the result of the derivative without modifying the elements in x since the array can be reused for further computations, e.g., the gradient \(\nabla g(\mathbf{x})\).

Parameters

i	the variable to derive with respect to.
x	a vector \(\mathbf{x}\).

Returns: the value of the partial derivative.

Exceptions

NullPointerException	if `x` is `null`.
IllegalArgumentException	if `x.length` does not correspond to the dimension of this function.
IndexOutOfBoundsException	if `i` is negative or greater than or equal to the dimension of this function.

Implements umontreal.ssj.util.MultivariateFunction.

Definition at line 97 of file RatioFunction.java.

◆ getDimension()

int umontreal.ssj.util.RatioFunction.getDimension ( )

Returns \(d\), the dimension of the function computed by this implementation.

If the dimension is not fixed, this method must return a negative value.

Returns: the dimension.

Implements umontreal.ssj.util.MultivariateFunction.

Definition at line 85 of file RatioFunction.java.

◆ getZeroOverZeroValue()

double umontreal.ssj.util.RatioFunction.getZeroOverZeroValue ( )

Returns the value returned by evaluate in the case where the \(0/0\) function is calculated.

The default value for

\(0/0\) is Double.NaN.

      Generally, @f$0/0@f$ is undefined, and therefore associated with
      the `Double.NaN` constant, meaning *not-a-number*. However, in
      certain applications, it can be defined differently to accomodate
      some special cases. For exemple, in a queueing system, if there are
      no arrivals, no customers are served, lost, queued, etc. As a
      result, many performance measures of interest turn out to
      be @f$0/0@f$. Specifically, the loss probability, i.e., the ratio
      of lost customers over the number of arrivals, should be 0 if there
      is no arrival; in this case, @f$0/0@f$ means 0. On the other hand,
      the service level, i.e., the fraction of customers waiting less
      than a fixed threshold, could be fixed to 1 if there is no arrival.

Returns: the value for \(0/0\).

Definition at line 71 of file RatioFunction.java.

◆ setZeroOverZeroValue()

void umontreal.ssj.util.RatioFunction.setZeroOverZeroValue ( double zeroOverZero )

Sets the value returned by evaluate for the undefined function \(0/0\) to zeroOverZero.

See getZeroOverZeroValue for more information.

Parameters

zeroOverZero the new value for \(0/0\).

Definition at line 81 of file RatioFunction.java.

The documentation for this class was generated from the following file:

src/main/java/umontreal/ssj/util/RatioFunction.java

SSJ API Documentation Stochastic Simulation in Java

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ RatioFunction() [1/2]

◆ RatioFunction() [2/2]

Member Function Documentation

◆ evaluate()

◆ evaluateGradient()

◆ getDimension()

◆ getZeroOverZeroValue()

◆ setZeroOverZeroValue()