org.apache.sysml.udf.lib

Class CumSumProd

java.lang.Object

org.apache.sysml.udf.PackageFunction

org.apache.sysml.udf.lib.CumSumProd

All Implemented Interfaces:

Serializable

public class CumSumProd
extends PackageFunction

Variant of cumsum:
Computes following two functions:

 
 cumsum_prod = function (Matrix[double] X, Matrix[double] C, double start)  return (Matrix[double] Y)
 # Computes the following recurrence in log-number of steps:
 # Y [1, ] = X [1, ] + C [1, ] * start;
 # Y [i+1, ] = X [i+1, ] + C [i+1, ] * Y [i, ]
 {
        Y = X; P = C; m = nrow(X); k = 1;
        Y [1, ] = Y [1, ] + C [1, ] * start;
        while (k < m) {
                Y [k+1 : m, ] = Y [k+1 : m, ] + Y [1 : m-k, ] * P [k+1 : m, ];
                P [k+1 : m, ] = P [1 : m-k, ] * P [k+1 : m, ];
                k = 2 * k;
        }
 }
 
 cumsum_prod_reverse = function (Matrix[double] X, Matrix[double] C, double start) return (Matrix[double] Y)
 # Computes the reverse recurrence in log-number of steps:
 # Y [m, ] = X [m, ] + C [m, ] * start;
 # Y [i-1, ] = X [i-1, ] + C [i-1, ] * Y [i, ]
 {
        Y = X; P = C; m = nrow(X); k = 1;
        Y [m, ] = Y [m, ] + C [m, ] * start;
        while (k < m) {
                Y [1 : m-k, ] = Y [1 : m-k, ] + Y [k+1 : m, ] * P [1 : m-k, ];
                P [1 : m-k, ] = P [k+1 : m, ] * P [1 : m-k, ];
                k = 2 * k;
        }
 }
 
 

The API of this external built-in function is as follows:

 
 func = externalFunction(matrix[double] X, matrix[double] C,  double start, boolean isReverse) return (matrix[double] Y) 
 implemented in (classname="org.apache.sysml.udf.lib.CumSumProd",exectype="mem");
 
 

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CumSumProd()

Method Summary

Modifier and Type	Method and Description
void	execute() Method that will be executed to perform this function.
FunctionParameter	getFunctionOutput(int pos) Method to get a specific output of this package function.
int	getNumFunctionOutputs() Method to get the number of outputs of this package function.

Methods inherited from class org.apache.sysml.udf.PackageFunction

createOutputFilePathAndName, execute, getBaseDir, getConfiguration, getFunctionInput, getNumFunctionInputs, hasVarNumFunctionOutputs, setBaseDir, setConfiguration, setFunctionInputs, setInput, setNumFunctionInputs

Methods inherited from class java.lang.Object

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

Constructor Detail

CumSumProd

public CumSumProd()

Method Detail

getNumFunctionOutputs

public int getNumFunctionOutputs()

Description copied from class: PackageFunction

Method to get the number of outputs of this package function. This method should be implemented in the user's function.

Specified by:

getNumFunctionOutputs in class PackageFunction

Returns:

number of outputs

getFunctionOutput

public FunctionParameter getFunctionOutput(int pos)

Description copied from class: PackageFunction

Method to get a specific output of this package function. This method should be implemented in the user's function.

Specified by:

getFunctionOutput in class PackageFunction

Parameters:

pos - function position

Returns:

function parameter

execute

public void execute()

Description copied from class: PackageFunction

Method that will be executed to perform this function.

Specified by:

execute in class PackageFunction