To compile : 

nvcc FILENAME.cu


To run :

./a.out MATRIX_SIZE NR_MULTIPLICATIONS


If correct you will get a diagonal matrix with NR_MULTIPLICATIONS on the diagonal :

1.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 
0.000000 1.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 
0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 0.000000 0.000000 
0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 0.000000 
0.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 
0.000000 0.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 
0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 1.000000 0.000000 
0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 1.000000