Prefer concatentation over connectLayers

[ManWithSleeve]

Compare:

convmixer-patches-are-all-you-need/convmixer/convMixerLayers.m

Lines 96 to 99 in 9770885

	lgraph = addLayers(lgraph, softmaxLayer('Name','softmax'));
	lgraph = addLayers(lgraph, classificationLayer('Name','classification'));
	lgraph = connectLayers(lgraph,'fc','softmax');
	lgraph = connectLayers(lgraph,'softmax','classification');

with

convmixer-patches-are-all-you-need/convmixer/convMixerLayers.m

Lines 88 to 93 in 9770885

	gapFc = [
	globalAveragePooling2dLayer(Name="GAP")
	fullyConnectedLayer(num_classes)
	];
	lgraph = addLayers(lgraph,gapFc);
	lgraph = connectLayers(lgraph,"batchnorm_"+2*depth,"GAP");

I think that the second is nicer as it only requires one call to addLayers and connectLayers

     out = [
         softmaxLayer(Name='softmax'))
         classificationLayer(Name='classification'))
     ];
     lgraph = addLayers(lgraph, out);
     lgraph = connectLayers(lgraph,'fc','softmax');

And then, because of the call to connectLayers I think it is better to explicitly name the final fully connected layer rather than reply on automatic naming, i.e., L90 should be fullyConnectedLayer(num_classes,Name='fc')

Another thing to consider is to concatenate the last two layers with the previous two before the call to addLayer, i.e.,

last = [
    globalAveragePooling2dLayer(Name="GAP")
    fullyConnectedLayer(num_classes)
];
if connectOutputLayers 
    last = [
        last
        softmaxLayer()
        classificationLayer()
    ];
end
lgraph = addLayers(lgraph,last);
lgraph = connectLayers(lgraph,"batchnorm_"+2*depth,"GAP");

With that version, you don't need to explicitly name most of the layers, just then ones that are referenced in the calls to connectLayers.