Made changes to allow ml module to work with big data.

modules/ml/include/opencv2/ml/ml.hpp

@@ -796,7 +796,7 @@ struct CV_EXPORTS CvDTreeTrainData
     const CvMat* responses;
     CvMat* responses_copy; // used in Boosting
 
-    int buf_count, buf_size;
+    int buf_count, buf_size; // buf_size is obsolete, please do not use it, use expression ((int64)buf->rows * (int64)buf->cols / buf_count) instead
     bool shared;
     int is_buf_16u;
 
@@ -806,6 +806,12 @@ struct CV_EXPORTS CvDTreeTrainData
 
     CvMat* counts;
     CvMat* buf;
+    inline size_t get_length_subbuf() const
+    {
+        size_t res = (size_t)(work_var_count + 1) * (size_t)sample_count;
+        return res;
+    }
+
     CvMat* direction;
     CvMat* split_buf;