sub min($$){ $_[0]<$_[1]?$_[0]:$_[1] };

my $app_w = 400;
my $app_h = 300;

my $image_w = 200;
my $image_h = 600;

my $y_scale = $app_w / $image_w;
my $x_scale = $app_h / $image_h;

my $factor = min $app_w,$app_h / min $image_w,$image_h;

printf("xs: %s, ys: %s, factor: %s", $x_scale, $y_scale, $factor);