Rather than just relying on the _cuda extension being built, also
check to see if we have valid GPU devices. If there aren't
GPU devices available, a warning saying:
UserWarning: CUDA extension is built, but disabling GPU support because of 'Cuda Error:
no CUDA-capable device is detected
Rather than just relying on the _cuda extension being built, also check to see if we have valid GPU devices. If there aren't GPU devices available, a warning saying:
will be logged, and GPU compatability disabled.