finding tiny faces中训练 hr_res101('train')出现问题

>> hr_res101('train')

ans =

    'models\widerface-resnet-101-simple-sample256-posfrac0.5-N25-bboxreg-cluster-scaled'

Trying to initialize the structure of resnet-101-simple
Unknown model: cannot initialize.
Loading pretrained weights from ./trained_models/imagenet-resnet-101-dag.mat
Loaded imdb from data\widerface\imdb.mat
cluster path: data\widerface\RefBox_N25_scaled.mat

opts = 

  包含以下字段的 struct:

      keepDilatedZeros: 0
             inputSize: [500 500]
          learningRate: [1×30 double]
               trainFn: '@cnn_train_dag_hardmine'
         batchGetterFn: '@cnn_get_batch_hardmine'
          freezeResNet: 0
                   tag: ''
            clusterNum: 25
           clusterName: 'scaled'
               bboxReg: 1
            skipLRMult: [0 1 0.1000]
            sampleSize: 256
           posFraction: 0.5000
             posThresh: 0.7000
             negThresh: 0.3000
                border: [0 0]
     pretrainModelPath: './trained_models/imagenet-resnet-101-dag.mat'
               dataDir: 'data\widerface'
             modelType: 'resnet-101-simple'
           networkType: 'dagnn'
    batchNormalization: 1
      weightInitMethod: 'gaussian'
        minClusterSize: [10 10]
        maxClusterSize: [Inf Inf]
                expDir: 'models\widerface-resnet-101-simple-sample256-posfrac0.5-N25-bboxreg-cluster-scaled'
             batchSize: 48
         numSubBatches: 1
             numEpochs: 50
                  gpus: [1 2 3 4]
       numFetchThreads: 8
                  lite: 0
              imdbPath: 'data\widerface\imdb.mat'
                 train: [1×1 struct]


ans = 

  包含以下字段的 struct:

                gpus: [1 2 3 4]
           batchSize: 48
       numSubBatches: 1
           numEpochs: 50
        learningRate: [1×30 double]
    keepDilatedZeros: 0

Start using dagnn.DetLoss for loss
cnn_train_dag_hardmine: resetting GPU
错误使用 cnn_train_dag_hardmine>prepareGPUs (line 616)
Error detected on workers 3 4.

出错 cnn_train_dag_hardmine (line 132)
  prepareGPUs(opts, epoch == start+1) ;

出错 cnn_widerface (line 212)
[net, info] = trainFn(net, imdb, getBatchFn(batchGetter, opts, net.meta), ...

出错 hr_res101 (line 41)
    cnn_widerface('inputSize', inputSize, ...

原因:
    错误使用 gpuDevice (line 26)
    Invalid CUDA device id: 3. Select a device id from the range 1:1.
    错误使用 gpuDevice (line 26)
    Invalid CUDA device id: 4. Select a device id from the range 1:1.
 

我电脑就一个gpu，这个gpuDevice怎么设置变成一个啊？
程序似乎是4个gpu什么的，没理解，有人知道怎么解决吗？
困扰了好久