load cblas 

var a = 
[
  8.0, 4, 7,
  3, 5, 1,
  1, 3, 2
];
 
var x = [ -1.0, 2, 1 ]

var y = [ 1.0, 0, 0 ]
 

io.writeln( a, x, y )
    
# y = Ax
cblas_dgemv(CblasRowMajor, CblasNoTrans, 3, 3, 1.0, a, 3, x, 1, 0.0, y, 1);

io.writeln( y )