cross-product

问题 Suppose I have two sets of points, A and B, in 2D space. I want to know if there exists a single straight line that will have all points of A on one side and all points of B on the other, and if possible, find one such line. I found this question while searching but it is more of a "line of best fit" problem. Intuitively, I feel like it is a question regarding cross-products but I can't figure out how it can be done. 回答1: You could find the convex hull for each set of points, and then follow

问题 Suppose I have two sets of points, A and B, in 2D space. I want to know if there exists a single straight line that will have all points of A on one side and all points of B on the other, and if possible, find one such line. I found this question while searching but it is more of a "line of best fit" problem. Intuitively, I feel like it is a question regarding cross-products but I can't figure out how it can be done. 回答1: You could find the convex hull for each set of points, and then follow

问题 I have a list with multiply identities and each identity consists of multiple images. When i am retrieving positive images from json list it works fine. After that I am mixing this positive list with by doing cross product with every images in pair form and then save in negative array. When i am doing cross product, my system got completely hang even i have 16 GB RAM with GPU. Code for i in range(0, len(idendities) - 1): for j in range(i + 1, len(idendities)): # print(samples_list[i], " vs "

问题 I have two vectors of integers, say v1=c(1,2) and v2=c(3,4) , I want to combine and obtain this as a result (as a data.frame, or matrix): > combine(v1,v2) <--- doesn't exist 1 3 1 4 2 3 2 4 This is a basic case. What about a little bit more complicated - combine every row with every other row? E.g. imagine that we have two data.frames or matrices d1, and d2, and we want to combine them to obtain the following result: d1 1 13 2 11 d2 3 12 4 10 > combine(d1,d2) <--- doesn't exist 1 13 3 12 1 13

问题 I'm trying to construct multiple cross products of traversables of different (but each homogeneous) types. The desired return type is a traversable of a tuple with the type matching the types in the input traversables. For example: List(1, 2, 3) cross Seq("a", "b") cross Set(0.5, 7.3) This should give a Traversable[(Int, String, Double)] with all possible combinations from the three sources. The case of combining only two sources was nicely answered here. The given idea is: implicit class

问题 I have the following piece of pseudo-C/Java/C# code: int a[]= { 30, 20 }; int b[] = { 40, 50 }; int c[] = {12, 12}; How do I compute the cross-product ABxAC? 回答1: The solution that was given to you in your last question basically adds a Z=0 for all your points. Over the so extended vectors you calculate your cross product . Geometrically the cross product produces a vector that is orthogonal to the two vectors used for the calculation, as both of your vectors lie in the XY plane the result

问题 Does the method for computing the cross-product change for left handed coordinates? 回答1: The formula for the cross product of the vectors (x1, x2, x3) and (y1, y2, y3) is z1 = x2 * y3 - x3 * y2 z2 = x3 * y1 - x1 * y3 z3 = x1 * y2 - x2 * y1 It is designed in a way that the three vectors x , y and z in the given order have the same handedness as the coordinate system itself. This property does not depend on the handedness of the coordinate system -- for a left-handed coordinate system the

问题 I am trying to use R to perform an operation (ideally with similarly displayed output) such as > x<-1:6 > y<-1:6 > x%o%y [,1] [,2] [,3] [,4] [,5] [,6] [1,] 1 2 3 4 5 6 [2,] 2 4 6 8 10 12 [3,] 3 6 9 12 15 18 [4,] 4 8 12 16 20 24 [5,] 5 10 15 20 25 30 [6,] 6 12 18 24 30 36 where each entry is found through addition not multiplication. I would also be interested in creating the 36 ordered pairs (1,1) , (1,2), etc... Furthermore, I want to use another vector like z<-1:4 to create all the ordered

问题 As the title says I want to calculate the surface normals of a given depth image by using the cross product of neighboring pixels. I would like to use Opencv for that and avoid using PCL however, I do not really understand the procedure, since my knowledge is quite limited in the subject. Therefore, I would be grateful is someone could provide some hints. To mention here that I do not have any other information except the depth image and the corresponding rgb image, so no K camera matrix

问题 I need to compare data on two different days in SQL. And I really need that in a single query since I need to use the results in pagination. Problem is, when I'm doing a self join it's results in duplicate columns since INNER JOIN is a cartesian product. Here's the code on sql fiddle E.g. SELECT * FROM `my_table` as t1 INNER JOIN my_table t2 ON t1.quality = t2.quality WHERE ( t1.day = '2015-01-08' OR t1.day = '2015-01-09' OR t2.day = '2015-01-08' OR t2.day = '2015-01-09' ) Two questions: How