org.apfloat.internal

## Class IntKaratsubaConvolutionStrategy

• All Implemented Interfaces:
Serializable, ConvolutionStrategy

```public class IntKaratsubaConvolutionStrategy
extends IntMediumConvolutionStrategy```
Convolution strategy using the Karatsuba algorithm. The complexity of the algorithm is O(nlog(3)/log(2)) as the operands are split to two and multiplied using three multiplications (and five additions / subtractions). This splitting is done recursively until some cut-off point where the basic O(n2) algorithm is applied. The Karatsuba algorithm is faster than the basic O(n2) multiplication algorithm for medium size numbers larger than some certain size. For very large numbers, the transform-based convolution algorithms are faster.
Since:
1.4
Version:
1.4
Author:
Mikko Tommila
Serialized Form
• ### Field Summary

Fields
Modifier and Type Field and Description
`static int` `CUTOFF_POINT`
Cut-off point for Karatsuba / basic convolution.
• ### Constructor Summary

Constructors
Constructor and Description
`IntKaratsubaConvolutionStrategy(int radix)`
Creates a convolution strategy using the specified radix.
• ### Method Summary

All Methods
Modifier and Type Method and Description
`DataStorage` ```convolute(DataStorage x, DataStorage y, long resultSize)```
Convolutes the two sets of data.
• ### Methods inherited from class org.apfloat.internal.IntBaseMath

`baseAdd, baseDivide, baseMultiplyAdd, baseSubtract`
• ### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ### Field Detail

• #### CUTOFF_POINT

`public static final int CUTOFF_POINT`
Cut-off point for Karatsuba / basic convolution.

Convolutions where the shorter number is at most this long are calculated using the basic O(n2) algorithm i.e. `super.convolute()`.

Constant Field Values
• ### Constructor Detail

• #### IntKaratsubaConvolutionStrategy

`public IntKaratsubaConvolutionStrategy(int radix)`
Creates a convolution strategy using the specified radix.
Parameters:
`radix` - The radix that will be used.
• ### Method Detail

• #### convolute

```public DataStorage convolute(DataStorage x,
DataStorage y,
long resultSize)
throws ApfloatRuntimeException```
Description copied from interface: `ConvolutionStrategy`
Convolutes the two sets of data.
Specified by:
`convolute` in interface `ConvolutionStrategy`
Overrides:
`convolute` in class `IntMediumConvolutionStrategy`
Parameters:
`x` - First data set.
`y` - Second data set.
`resultSize` - Number of elements needed in the result data.
Returns:
The convolved data.
Throws:
`ApfloatRuntimeException`