I usually implement the program using the OpenCV library through visual Studio. Every time the following problems occur, they bother me.
Mat temp(Size(width, height), CV_64F); temp.at(<) <------ this problem
In order to access Mat type data, I have to use syntax like '.at<type>(x, y)'. But when I input '<', your software make automatically '(<)'. So I always delete '(' and ')'.