c++ - Convert a 2D array into an Armadillo matrix (mat) object

Question

How do I convert a standard C++ 2D array into an Armadillo mat object representing a matrix, so that I can perform matrix operations?

For example, I want to convert from:

double a[10][20];

to:

arma::mat A;

question from:https://stackoverflow.com/questions/65868229/convert-a-2d-array-into-an-armadillo-matrix-mat-object

Answer 1

Use

arma::mat A(&a[0][0], 10, 20);

if you want a copy of the buffer and:

arma::mat A(&a[0][0], 10, 20, false);

if you want to use the buffer pointed out by a, for more detailed information see http://arma.sourceforge.net/docs.html#Mat