C++ invert matrix

Question

The following dynamic array contains a non-symmetric n*n matrix (with n <=100):

int **matrix;
matrix = new int*[n];
for (int i = 0; i < n; i++)
    matrix[i] = new int[n];

Is there an extremely easy way to invert it? Ideally I'd only use something from the STL or download a single header file.

what do you mean by invert? try to give some sample input and output for it — Adrian, Mar 08 '12 at 14:20
I mean find the inverse of: http://en.wikipedia.org/wiki/Invertible_matrix — pockethook, Mar 08 '12 at 14:23
@Adrian Since he calls this thing an nxn-matrix it seems rather obvious what he means by inversion. — Christian Rau, Mar 08 '12 at 14:24

score 10 · Accepted Answer · answered Mar 08 '12 at 14:21

Using Eigen.

http://eigen.tuxfamily.org/index.php?title=Main_Page

You can map your array to an Eigen matrix and then perform efficient matrix inversion.

You must only include it.

I add that usually if you have to perform your inversion for linear system solving, it's better to use a matrix decomposition based on the properties of the matrix that you can exploit.

http://eigen.tuxfamily.org/dox/TutorialLinearAlgebra.html

score 3 · Answer 2 · answered Mar 08 '12 at 14:19

3

Not extremely easy but it works: Numerical Recipes in c page 48, using LU decomposition.

answered Mar 08 '12 at 14:19

assylias

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Looks to be an interesting book! Just ordered one, should be a handy reference tool. – john Oct 04 '12 at 16:12
@john the C part of the book is actually free (but admittedly not very user friendly when browsing) – assylias Oct 04 '12 at 16:17

C++ invert matrix

2 Answers2