Add Range function for XTensor.

source/tensor/XTensor.cpp

@@ -2114,6 +2114,36 @@ void XTensor::FreeData(XTensor * tensor, XMem * myMem, bool useBuf)
     tensor->isInGlobalMem = false;
 }
 
+/*  set the tensor with an data array
+>> tensor - XTensor. it must be on CPU
+>> start - the begin of the array
+>> end - the end of the array (not included self)
+>> step - the step of two items
+*/
+void XTensor::Range(XTensor * tensor, int start, int end, int step)
+{
+    if (tensor == NULL)
+        return;
+    /* get the length of tensor */
+    int length = tensor->GetDim(0);
+
+    /* compute the true length according to the (start, end, step) */
+    int a = abs(end - start);
+    int freq = ceil(1.0 * a / abs(step));
+
+    /* init a integer array to store the sequence */
+    int* index = new int[freq];
+    for (int i = 0; i < freq; i++)
+        index[i] = start + i * step;
+
+    CheckNTErrors((length == freq), "the length of the tensor is not matched");
+
+    /* set the data from the array */
+    tensor->SetData(index, freq);
+
+    delete[] index;
+}
+
 /*************************************************
 * we define the "new and delete" functions below
 */

source/tensor/XTensor.h

@@ -443,6 +443,10 @@ public:
     /* free the memory space of the matrix (in the global memory) */
     static
     void FreeData(XTensor * matrix, XMem * myMem = NULL, bool useBuf = false);
+
+    /* generate the range tensor by start, end and the step */
+    static
+    void Range(XTensor * tensor, int start, int end, int step);
 };
 
 /* we make a unique id for every tensor */