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SSJ V. 2.6. |
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public interface MultivariateFunction
Represents a function of multiple variables. This interface specifies a method evaluate that computes a g(x) function, where x = (x0,…, xd-1)∈Rd. It also specifies a method evaluateGradient for computing its gradient ∇g(x).
The dimension d can be fixed or variable. When d is fixed, the methods specified by this interface always take the same number of arguments. This is the case, for example, with a ratio of two variables. When d is variable, the implementation can compute the function for a vector x of any length. This can happen for a product or sum of variables.
The methods of this interface take a variable number of arguments to accomodate the common case of fixed dimension with more convenience; the programmer can call the method without creating an array. For the generic case, however, one can replace the arguments with an array.
Method Summary | |
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double |
evaluate(double... x)
Computes the function g(x) for the vector x. |
double |
evaluateGradient(int i,
double... x)
Computes ∂g(x)/∂xi, the derivative of g(x) with respect to xi. |
int |
getDimension()
Returns d, the dimension of the function computed by this implementation. |
Method Detail |
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int getDimension()
double evaluate(double... x)
x
- a vector
x.
NullPointerException
- if x is null.
IllegalArgumentException
- if x.length
does not correspond to the dimension of this function.double evaluateGradient(int i, double... x)
i
- the variable to derive with respect to.x
- a vector
x.
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.
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SSJ V. 2.6. |
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