Your question title might be “How can I use NARX network on GPU” or “How can I train NARX network on GPU”, and “How can I use NARX network with multi-input”. Generally, one question should be related to one title. Wrong title makes the answers confusing. Tips for asking good questions to get accurate answers quickly may help you to write a good question.
1. GPU memory size: NVIDIA GeForce GTX 750 Ti has 2GB GPU memory. Have you checked the volume of your data? Is it lower than 2GB? In case of GPU calculation, you need to pay attention to the amount of your GPU memory.
2. GPU vs CPU: In case of small calculation, CPU is much much much faster than GPU. This is because GPU calculation needs a transfer sequence from RAM to GPU memory. See and check the following code.
[X,T] = simpleseries_dataset;
Xnew = X(81:100);
X = X(1:80);
T = T(1:80);
net = narxnet(1:2,1:2,10);
[Xs,Xi,Ai,Ts] = preparets(net,X,{},T);
tic
net1 = train(net,Xs,Ts,Xi,Ai,'useGPU','no');
toc
net2 = train(net,Xs,Ts,Xi,Ai,'useGPU','yes');
toc
3. NARXnet with multi-input: The following Q&A might help you.
https://jp.mathworks.com/matlabcentral/answers/302908-narxnet-with-multi-input
HTH
