##
jwo.utils

Class JWLUDecomp

java.lang.Object
**jwo.utils.JWLUDecomp**

- public class
**JWLUDecomp** - extends Object

Class for finding the solution of a set of linear
algrbraic equations via LU decomposition.
Adapted from the algorithm documented in Numerical
Receipes in C (Press *et al*, 1988, pp.43-45).

**Version:**
- 2.2, 23rd November, 2003.
**Author:**
- Jo Wood

**Constructor Summary** |

**JWLUDecomp**(float[][] lhs)
Creates the LU Decomposed matrix based on LHS of a set of
normal equations equations. |

**JWLUDecomp**(float[][] lhs,
float[] rhs)
Solves a set of linear equations provided by a matrix holding the
left hand side and a vector holding the right hand side. |

**Method Summary** |

` float[]` |
**getCoeff**()
Reports the solved coefficients. |

` void` |
**luBackSub**(float[] rhs)
Performs forward and back substitution on an LU decomposed
matrix. |

**Methods inherited from class java.lang.Object** |

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

###
JWLUDecomp

public **JWLUDecomp**(float[][] lhs,
float[] rhs)

- Solves a set of linear equations provided by a matrix holding the
left hand side and a vector holding the right hand side. The number of
rows corresponds to the number of equations, the number of columns
corresponds to the number of unknowns. It therefore follows that the
left hand side of the equation must have at least as many rows as columns.
This constructor will convert the expression into a set of normal
equations before using LU decomposition to solve the equations.

**Parameters:**`lhs`

- Matrix holding LHS of equations to solve.`rhs`

- Vector holding RHS of equations to solve.

###
JWLUDecomp

public **JWLUDecomp**(float[][] lhs)

- Creates the LU Decomposed matrix based on LHS of a set of
normal equations equations.

**Parameters:**`lhs`

- Matrix holding LHS of normal equations to solve.

###
getCoeff

public float[] **getCoeff**()

- Reports the solved coefficients. The RHS of the equation must
have been given through a constructor. Alternatively use luBackSub()
to calculate on the fly.

**Returns:**- Solved coeffients.

###
luBackSub

public void **luBackSub**(float[] rhs)

- Performs forward and back substitution on an LU decomposed
matrix.

**Parameters:**`rhs`

- RHS of equations to be solved. The array of supplied
values gets replaced with the solved coeffients.

*Copyright Jo Wood, 1996-2005, last modified, 11th March, 2005*