##
LUDC

The
LUDC
procedure replaces an *
n*
by *
n*
array, *
A*
, with the
LU decomposition of a row-wise permutation of itself.

LUDC is based on the routine ```
ludcmp
```

described in section 2.3 of *
Numerical Recipes in C: The Art of Scientific Computing*
(Second Edition), published by Cambridge University Press, and is used by permission.

###
Calling Sequence

LUDC, *
A, Index*

###
Arguments

####
A

An *
n*
by *
n*
array of any type except string. Upon output, *
A*
is replaced with its LU decomposition.

####
Index

An output vector that records the row permutations which occurred as a result of partial pivoting.

###
Keywords

####
COLUMN

Set this keyword if the input array *
A*
is in column-major format (composed of column vectors) rather than in row-major format (composed of row vectors).

####
DOUBLE

Set this keyword to force the computation to be done in double-precision arithmetic.

####
INTERCHANGES

An output variable that is set to positive 1 if the number of row interchanges was even, or to negative 1 if the number of interchanges was odd.

###
Example

See the description of LUSOL for an example using this function.