defaultStr = parallel.gpu.RandStream.getGlobalStream

defaultStr =

Threefry4x64_20 random stream on the GPU (current global stream)
             Seed: 0
  NormalTransform: BoxMuller

If you change the global stream, you can use the stream defaultStr to restore the default settings. For example, suppose that you change the global stream to a different stream.

newStr = parallel.gpu.RandStream('CombRecursive', 'NormalTransform','Inversion');
defaultStr = parallel.gpu.RandStream.setGlobalStream(newStr)

defaultStr =

Threefry4x64_20 random stream on the GPU
             Seed: 0
  NormalTransform: BoxMuller

defaultStr is no longer the current global GPU stream. Once you finish your calculations using the new global stream settings, you can reset the stream to the default settings.

newStr = parallel.gpu.RandStream.setGlobalStream(defaultStr)

newStr =

MRG32K3A random stream on the GPU
             Seed: 0
  NormalTransform: Inversion

defaultStr

defaultStr =

Threefry4x64_20 random stream on the GPU (current global stream)
             Seed: 0
  NormalTransform: BoxMuller

defaultStr is once again the current global stream.