Programmer Think

Linear model and regression Objective: to learn a linear model to predict real value output markers as accurately as possible. Where yi is the actual observed value and f (xi) is the regression value. General form: Where x=(x1, x2,..., xd) is the sample described by the d-dimensional attribute, where xi is the value of X on the ith at ...

Wave series This problem really takes time to understand the details. Idea: As shown in the figure below, the first item of the sequence is x, the tolerance is set, set={a, - b}; From the first picture below, we can know that the number of set s is n*(n-1)/2 (formula: first term plus last term divided by 2) We let cnt=n*(n-1)/2 (that is, t ...

c++ opencv pixel value operation - auxiliary document corner judgment There is a set of corner coordinates of corners of vector < point > type (obtained by fitting the document border and calculating the intersection) There is also a binary document contour map of Mat type (the document image is obtained by Canny contour extraction + fin ...

c + + programming module In the function header or prototype parameter, int arr [] is equivalent to in t *arr Because the array name can be regarded as a pointer, the array name is interpreted as the address of the first element arr[i] == *(arr+i) &arr[i] = arr + i The above advantages of passing by array or pointer: Save the time cos ...

Which methods are invoked in the process of object usage? Code example 1 class Test { public: Test(int a = 10) :ma(a) { cout << "Test(int)" << endl; } ~Test() { cout << "~Test()" << endl; } Test(const Test &t) :ma(t.ma) { cout << "Test(const Test&)" << endl; } Test& operator=(const Tes ...

Chapter III data semantics Data member binding timing Summary: ==The compiler starts to parse the member function myfunc after the entire class A is defined== Because only after the entire class A is defined, Only when the compiler can see the myvar in class A, can it make the above appropriate explanation for the occurrence of myvar acco ...

"Wuji, how much do you remember what I taught you?" "Master Hui, I only remember more than half." "And now?" "There is less than half left." "And now?" "I've forgotten everything!" "OK, you can go!" Envy Zhang Wuji, forget his martial arts and defeat the enemy; I forgot my ...

C + + performance test (I) Write in front Test environment: Operating system: windows11 Compiler: msvc14 remarks: It is recommended that those with c + + foundation come back to this blog, because I will not explain some functions or methods of c + + (because I may also check now). Of course, if there are any questions, I can answer them i ...

1, Constructor         1. How the constructor looks                 (1) . the function name and class name are the same                 (2) . no return value class Person { public: Person(){}//Constructor -- > has no return value prote ...

1, KNN principle 1.1 introduction to KNN principle    KNN algorithm, i.e. K nearest neighbor algorithm, as the name suggests, its principle is to judge which category x belongs to according to what category most of the K nearest points belong to when predicting a new value X. zzzzMing - big data technology - simple KNN algor ...