de.caff.generics.function

Interface VarDoubleOperator

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface VarDoubleOperator

Primitive double operator with a variable number of arguments.

Although this basically works for a variable double array via the apply(double...) method implementors have to implement the method apply(DoubleIndexable) with a DoubleIndexable argument. This is done to make this class generally more useful without the need to copy arrays.

An example using the maxOp operator defined in the documentation of fromBinary(DoubleBinaryOperator, double) should illustrate this (with Point2D arguments):

 double maxX = maxOp.apply(DoubleIndexable.viewArray(Point2D::getX,
                                                     p1, p2, p3, p4));
 

Since:

November 03, 2020

Author:

Rammi

Method Summary

Modifier and Type	Method and Description
default double	apply(double... values) Apply this operator.
double	apply(DoubleIndexable values) Apply this operator.
static VarDoubleOperator	fromBinary(java.util.function.DoubleBinaryOperator binaryOp, double startValue) Create an variable args operator from applying a binary operator over and over.

Method Detail

apply

default double apply(double... values)

Apply this operator. This default method forwards execution to apply(DoubleIndexable).

Parameters:

values - arguments on which this operator is applied

Returns:

result of applying this operator to all arguments

apply

double apply(@NotNull
             DoubleIndexable values)

Apply this operator.

Parameters:

values - indexable providing the values on which this operator operates

Returns:

result of applying this operator to all values

fromBinary

@NotNull
static VarDoubleOperator fromBinary(@NotNull
                                             java.util.function.DoubleBinaryOperator binaryOp,
                                             double startValue)

Create an variable args operator from applying a binary operator over and over.

Eg

 VarDoubleOperator maxOp = VarDoubleOperator.fromBinary(Math::max, Double.NEGATIVE_INFINITY);
 double max = maxOp.apply(1, -7, Math.PI, Math.atan(17));
 

On each application the currently accumulated result becomes the left (first) argument of binaryOp, while the run value becomes the right (second).

Parameters:

binaryOp - binary operator

startValue - start value (result of operator if no values are given)

Returns:

variable double argument operator which applies the given binary operator over and over