math

问题 I am creating a game where I want an enemy to path track onto the player - who can move in any direction on the 2D plane. At first, I tried... self.bat_x += (player_rect.centerx - self.rect.centerx) / 60 self.bat_y += (player_rect.centery - self.rect.centery) / 60 Here the path-tracking works fine. I divide each value by 60 so that the enemy doesn't just appear and stick on to my player / to slow the movement of the enemy down. However, the further away the enemy is, the faster it is. The

问题 Objective Starting from a line soup with many overlying lines. Group these coincident lines and sum the number of lines. Divide this sum to the highest sum in the assembly to get the relative amount. Use this relative amount as a measurement for the line density. State of work One possibility that comes to my mind is to create a "Line" Class (or use shapely LineString) to calculate the distance between line pairs. In a coincident case, P_1 and P_2 of line_i are on line_j. For the application,

问题 I have read numerous topics and articles and official MYSQL docs but nowhere I have find something that would help me understand how to solve this. Even this SO topic failed to do what I need (in it, they didn't try to search value bigger then 2, you'll see why that is a problem). For example I have ranges defined in range_and_prices table: --- | id | ranges_from | ranges_to | prices | | --- | ----------- | --------- | ------ | | 1 | 1 | 20 | 10 | | 2 | 21 | 40 | 20 | | 3 | 41 | 60 | 40 When

问题 I have read numerous topics and articles and official MYSQL docs but nowhere I have find something that would help me understand how to solve this. Even this SO topic failed to do what I need (in it, they didn't try to search value bigger then 2, you'll see why that is a problem). For example I have ranges defined in range_and_prices table: --- | id | ranges_from | ranges_to | prices | | --- | ----------- | --------- | ------ | | 1 | 1 | 20 | 10 | | 2 | 21 | 40 | 20 | | 3 | 41 | 60 | 40 When

问题 I have a IP Camera which can PTZ. I am currently streaming live feed into the browser and want to allow user to click a point on the screen and the camera will pan and tilt so that the user clicked position will now become the center point of view. my Camera Pan 360 degrees and Tilt from -55 to 90. any algorithm that will guide to me achieve my goal ?? 回答1: Let's start by declaring a 3D coordinate system around the camera (the origin). I will use the following: The z-axis points upwards. The

问题 What is the usual way to do math, addition, subtraction, on PCL (Point Cloud Library) data types, i.e. PointXYZ? There don't seem to be operators defined even for the basics. I thought maybe the PCL way was to convert to Eigen vectors, but there doesn't seem to be a constructor for that either. 回答1: For anyone who wants to do basic math with PointXYZ , here a quick example: pcl::PointXYZ a(0, 1, 2), b(10, 20, 30), c; c.getArray3fMap() = a.getArray3fMap() + b.getArray3fMap(); std::cout << "c="

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . I'm looking to mode the solar system within c++ and openGL, and I was wondering if there was a cheap method that I could produce that would return an x,y,z vector that I could use to update the position of each

问题 Given these strings: "1 + 2" "apple,pear" How can I use Python 3(.5) to determine that the first string contains a math problem and nothing else and that the second string does not? 回答1: Here is a way to do it: import ast UNARY_OPS = (ast.UAdd, ast.USub) BINARY_OPS = (ast.Add, ast.Sub, ast.Mult, ast.Div, ast.Mod) def is_arithmetic(s): def _is_arithmetic(node): if isinstance(node, ast.Num): return True elif isinstance(node, ast.Expression): return _is_arithmetic(node.body) elif isinstance(node

问题 Given these strings: "1 + 2" "apple,pear" How can I use Python 3(.5) to determine that the first string contains a math problem and nothing else and that the second string does not? 回答1: Here is a way to do it: import ast UNARY_OPS = (ast.UAdd, ast.USub) BINARY_OPS = (ast.Add, ast.Sub, ast.Mult, ast.Div, ast.Mod) def is_arithmetic(s): def _is_arithmetic(node): if isinstance(node, ast.Num): return True elif isinstance(node, ast.Expression): return _is_arithmetic(node.body) elif isinstance(node

问题 In java, I know the data type of the result of an arithmetic calculation depends on the data types of the numbers involved in the calculation. For example, int + int = int long/double=double a. But I can't find any references which can give me all these rules. Could someone help me? b. How to avoid over flow in arithmetic calculation? For example, the results of 2 long may not fit into a long anymore... Thanks a lot. 回答1: a. These rules are called numeric promotion rules and are specified in