Output for LU Decomposition

A 4-by-4 matrix has been taken to
test the working of LU decomposition.
Change to include ludec
Identtiy matrix and formatting

Display method has been changed to include
basic formatting which displays elements as
fixed floating point numbers with 4 digits
of precision. This has to be modified further
so as include all cases.

eye() function has been added which converts
any square matrix to the corresponding
identity matrix.
LU Decomposition

Factorizes the matrix A into Lower Triangular Matrix L
,Upper Triagular Matrix U and a Permutation Matrix P
which is required to satisfy PA = LU. For the permu-
tation matrix the function doesn't directly take n-by-n
input but instead it takes a vector<int> which contains
the row indices of 1 as permutation matrix consists of
only 1 and 0.

Suppose after executing the function a 4-by-1 P is given
by '0 2 3 1' then the corresponding 4-by-4 permutation
matrix can generated by setting Perm(0, 0) , Perm(1, 2),
Perm(2, 3) and Perm(3, 1) to 1.
Makefile for LU Decomposition