Parallel Colt 0.7.2

## cern.colt.matrix.tdouble.algo.solver.preconditioner Class DoubleDiagonal

```java.lang.Object
cern.colt.matrix.tdouble.algo.solver.preconditioner.DoubleDiagonal
```
All Implemented Interfaces:
DoublePreconditioner

`public class DoubleDiagonalextends Objectimplements DoublePreconditioner`

Diagonal preconditioner. Uses the inverse of the diagonal as preconditioner

Constructor Summary
`DoubleDiagonal(int n)`
Constructor for DiagonalPreconditioner

Method Summary
` DoubleMatrix1D` ```apply(DoubleMatrix1D b, DoubleMatrix1D x)```
Solves the approximate problem with the given right hand side.
` void` `setMatrix(DoubleMatrix2D A)`
Sets the operator matrix for the preconditioner.
` DoubleMatrix1D` ```transApply(DoubleMatrix1D b, DoubleMatrix1D x)```
Solves the approximate transpose problem with the given right hand side.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DoubleDiagonal

`public DoubleDiagonal(int n)`
Constructor for DiagonalPreconditioner

Parameters:
`n` - Problem size (number of rows)
Method Detail

### apply

```public DoubleMatrix1D apply(DoubleMatrix1D b,
DoubleMatrix1D x)```
Description copied from interface: `DoublePreconditioner`
Solves the approximate problem with the given right hand side. Result is stored in given solution vector

Specified by:
`apply` in interface `DoublePreconditioner`
Parameters:
`b` - Right hand side of problem
`x` - Result is stored here
Returns:
x

### transApply

```public DoubleMatrix1D transApply(DoubleMatrix1D b,
DoubleMatrix1D x)```
Description copied from interface: `DoublePreconditioner`
Solves the approximate transpose problem with the given right hand side. Result is stored in given solution vector

Specified by:
`transApply` in interface `DoublePreconditioner`
Parameters:
`b` - Right hand side of problem
`x` - Result is stored here
Returns:
x

### setMatrix

`public void setMatrix(DoubleMatrix2D A)`
Description copied from interface: `DoublePreconditioner`
Sets the operator matrix for the preconditioner. This method must be called before a preconditioner is used by an iterative solver

Specified by:
`setMatrix` in interface `DoublePreconditioner`
Parameters:
`A` - Matrix to setup the preconditioner for. Not modified

Parallel Colt 0.7.2