vector

问题 I think there will be much more people interested into this subject. I have some specific task to do in the most efficient way. My base data are: - time indices of buy and sell signals - on the diag of time indicies I have ROC (rate of change) between closest buy-sell pairs: r <- array(data = NA, dim = c(5, 5), dimnames = list(buy_idx = c(1,5,9,12,16), sell_idx = c(3,7,10,14,19))) diag(r) <- c(1.04,0.97,1.07,1.21,1.1) The task is to generate moving compound ROC on every possible window (buy

问题 I think there will be much more people interested into this subject. I have some specific task to do in the most efficient way. My base data are: - time indices of buy and sell signals - on the diag of time indicies I have ROC (rate of change) between closest buy-sell pairs: r <- array(data = NA, dim = c(5, 5), dimnames = list(buy_idx = c(1,5,9,12,16), sell_idx = c(3,7,10,14,19))) diag(r) <- c(1.04,0.97,1.07,1.21,1.1) The task is to generate moving compound ROC on every possible window (buy

问题 This question already has an answer here : Vector vs Collections.synchronizedList(ArrayList) (1 answer) Closed 7 years ago . If multiple threads access vector, vector will ensure that only one thread can access the vector at the same time. SynchronizedList is same. So what's the difference? How to choose in some synchronous situation? 回答1: The main reason for this redundancy is backward compatibility with java code developed for old versions of Java. If I remember correctly before Java 1.2

问题 I'm using a external library which at some point gives me a raw pointer to an array of integers and a size. Now I'd like to use std::vector to access and modify these values in place, rather than accessing them with raw pointers. Here is an articifial example that explains the point: size_t size = 0; int * data = get_data_from_library(size); // raw data from library {5,3,2,1,4}, size gets filled in std::vector<int> v = ????; // pseudo vector to be used to access the raw data std::sort(v.begin

问题 I'm using a external library which at some point gives me a raw pointer to an array of integers and a size. Now I'd like to use std::vector to access and modify these values in place, rather than accessing them with raw pointers. Here is an articifial example that explains the point: size_t size = 0; int * data = get_data_from_library(size); // raw data from library {5,3,2,1,4}, size gets filled in std::vector<int> v = ????; // pseudo vector to be used to access the raw data std::sort(v.begin

问题 Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 1 year ago . Improve this question Suppose we have a=60 and B=60 . I am trying to calculate this area: when I try this: W = ((u^2)* cot(B) + (v^2 * cot(a))/8; I get this error: Incorrect dimensions for raising a matrix to a power. Check that the matrix is square and the power is a scalar. To

问题 I need to find the cosine similarity between two frequency vectors in MATLAB. Example vectors: a = [2,3,4,4,6,1] b = [1,3,2,4,6,3] How do I measure the cosine similarity between these vectors in MATLAB? 回答1: Take a quick look at the mathematical definition of Cosine similarity. From the definition, you just need the dot product of the vectors divided by the product of the Euclidean norms of those vectors. % MATLAB 2018b a = [2,3,4,4,6,1]; b = [1,3,2,4,6,3]; cosSim = sum(a.*b)/sqrt(sum(a.^2)

问题 I am new to MATLAB and currently working on my homework assignment. I am trying to declare the x variable as the following: Create a linearly spaced array x of size (1 × 200) comprising values ranging from –pi to pi . I've tried this code: x=[-pi:200:pi]; but I'm not sure if it's the correct way to do this or not. 回答1: You can use linspace as follow: x = linspace(-pi, pi, 200); check this out for an example: https://www.mathworks.com/help/matlab/ref/linspace.html 回答2: The other answer shows

问题 This question already has answers here : What is array to pointer decay? (9 answers) Closed 2 years ago . I came across a piece of C++ code in one of my projects that initializes a vector with two inputs. One of the inputs is an existing array, and the other is the same array plus the array length. I found a similar piece of code on another site: // Create an array of string objects std::string arr[] = {"first", "sec", "third", "fourth"}; // Initialize vector with a string array std::vector

问题 Why is the time complexity required for swapping contents of two C++ STL vectors independent of the size of the corresponding vectors? Reference: http://www.cplusplus.com/reference/vector/vector/swap/ 回答1: A typical vector implementation stores: The allocator A pointer to the first element A pointer to the past-the-end position, or equivalently, the size A pointer to the end of the memory block owned by the vector, or equivalently, the capacity swap() simply swaps the pointers, and, if