GPU-based Cube CNN

Add supprot for multiple GPUs in version 2.0

1. Install CUDA and nvcc compiler

2. Download GCN from https://github.com/jdjd1114/GCN  
   bash git clone https://github.com/jdjd1114/GCN.git
   bash cd path_to_GCN/

3. Compile (Note that MATLAB path in Makefile may need to be modified.)
   bash make

4. run the program  
   bash ./bin/gcn data/DATASET.mat device_id  
   DATASET.mat consists of three parts:
   * Dataset, a 3-dimensional hyperspectal image
   * labels, a 2-dimensional label matrix
   * Device ID

5. run GCN_version_2.0 ( Multiple GPUs verison )
   modify SRC in Makefile (src/hyper_version_mGPU.cu)
   recompile with Makefile
   bash make
   bash ./bin/gcn data/DATASET.mat device_num master_dev_id