use strict;
use warnings;

use AI::MXNet qw(mx);

# specify which context we want this dataflow to be executed in
# for CPU use mx->cpu(0); (note, (0) does not mean cpuid or something, it is not used)
# for GPU use mx->gpu(0); (0 denotes gpu device id)

my $ctx = mx->cpu(0);

# create 1D arrays with values: 1, 2, 3, 4 for a b c d respectively
# these are DATA
my $a_data = mx->nd->array([1], ctx => $ctx);
my $b_data = mx->nd->array([2], ctx => $ctx);
my $c_data = mx->nd->array([3], ctx => $ctx);
my $d_data = mx->nd->array([4], ctx => $ctx);

# these are SYMBOLS
my $a = mx->symbol->Variable('A');
my $b = mx->symbol->Variable('B');
my $c = mx->symbol->Variable('C');
my $d = mx->symbol->Variable('D');

# these is the EXPRESSION to evaluate
# basically our dataflow graph (but still no data on it, just description)
my $e = ($a*$b) + ($c*$d);

print "e=".$e."\n";

# this is how we associate data with symbols and specify
# whether we want to run this on CPU or GPU
my $exe = $e->bind(
	ctx => $ctx,
        # this is how we bind data to symbols so our dataflow graph can be "executed"
        # and a result comes out
        # Note: create the arrays on the same device as executing them, i.e. context, ctx,
        # must be the same here and above in creating the arrays.
	args => {'A'=>$a_data, 'B'=>$b_data, 'C'=>$c_data, 'D'=>$d_data}
);
# propage inputs to the output(s)
$exe->forward(1);

# we need the first (and only one at this case) output as PDL array
print "output: ".$exe->outputs->[0]->aspdl."\n";