diff --git a/stim/cuda/cudatools/devices.h b/stim/cuda/cudatools/devices.h
index 9b32b38..249d7e0 100644
--- a/stim/cuda/cudatools/devices.h
+++ b/stim/cuda/cudatools/devices.h
@@ -1,5 +1,5 @@
-#ifndef RTS_CUDA_DEVICES
-#define RTS_CUDA_DEVICES
+#ifndef STIM_CUDA_DEVICES
+#define STIM_CUDA_DEVICES
 
 #include <cuda.h>
 
@@ -35,11 +35,15 @@ namespace stim{
 	bool testDevice(int d, int major, int minor){
 		int nd;
 		cudaGetDeviceCount(&nd);		//get the number of CUDA devices
-		if(d < nd && d > 0)	{		//if the given ID has an associated device
+		if(d <= nd && d >= 0)	{		//if the given ID has an associated device
 			cudaDeviceProp props;
 			cudaGetDeviceProperties(&props, d);	//get the device properties structure
-			if(props.major >= major && props.minor >= minor)
-					return true;
+			if(props.major > major){
+				return true;
+			}
+			else if(props.major == major && props.minor >= minor){
+				return true;
+			}
 		}
 		return false;
 	}
@@ -54,6 +58,23 @@ namespace stim{
 		}
 		return valid;
 	}
+
+	void printDevice(int device){
+		int nd;
+		cudaGetDeviceCount(&nd);		//get the number of CUDA devices
+		printf("CUDA Device Diagnosis: [%i]\n", device);
+		if(device < 0){
+			printf("Device %i is an invalid device ID\n", device);
+		}
+		else if(device >= nd){
+			printf("Device %i is unavailable - only %i devices are detected", device, nd);
+		}
+		else{
+			cudaDeviceProp props;
+			cudaGetDeviceProperties(&props, device);	//get the device properties structure
+			printf("compute capability: %i.%i\n", props.major, props.minor);
+		}
+	}
 }	//end namespace rts
 
 #endif
--
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