Add more information and correct indentation of error messages in dnn_sptf

theano/gpuarray/c_code/dnn_sptf.c

@@ -63,14 +63,14 @@ dnn_sptf(PyGpuArrayObject * input,
         break;
     default:
         PyErr_SetString( PyExc_TypeError,
-                         "GpuDnnTransformer: unsupported type in spatial transformer sampler" );
+            "GpuDnnTransformer: unsupported type for input in spatial transformer." );
         return -1;
     }
 
     if ( ! GpuArray_IS_C_CONTIGUOUS( &(input->ga) ) )
     {
         PyErr_SetString( PyExc_MemoryError,
-                         "GpuDnnTransformer: input data is not C-contiguous" );
+            "GpuDnnTransformer: input data is not C-contiguous." );
         return -1;
     }
 
@@ -78,7 +78,8 @@ dnn_sptf(PyGpuArrayObject * input,
          theta->ga.typecode != GA_DOUBLE &&
          theta->ga.typecode != GA_HALF )
     {
-        PyErr_SetString( PyExc_TypeError, "GpuDnnTransformer: unsupported data type for theta" );
+        PyErr_SetString( PyExc_TypeError,
+            "GpuDnnTransformer: unsupported data type for theta in spatial transformer." );
         return -1;
     }
     else if ( PyGpuArray_NDIM( theta ) != 3 )
@@ -245,8 +246,9 @@ dnn_sptf(PyGpuArrayObject * input,
 
     if ( CUDNN_STATUS_SUCCESS != err )
     {
-        PyErr_SetString( PyExc_RuntimeError,
-                         "GpuDnnTransformer: failed to create grid sampler" );
+        PyErr_Format( PyExc_RuntimeError,
+            "GpuDnnTransformer: failed to create grid sampler: %s",
+            cudnnGetErrorString( err ) );
         spatialtf_context_destroy( &spatialtf_ctx );
         cuda_exit( gpu_ctx->ctx );
         return -1;