Numerical Methods
1.1 Random numbers
head File
#include<random>
Random Number Overview
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random number distribution. The distribution of random numbers distribution
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Random number engine. Generate random number engin. source of randomness
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Random number generator. A random number generator is composed of a random number engine and a random number distribution.
Operation of the random number engine
- The compiler will automatically select a random number engine as the engine of the type default_random_engine.
default_random_engine e;
cout<<e()<<endl;
Operations on Random Number Distributions
- Need to choose a distribution sequence for the default random number engine.
uniform_int_distribution<unsigned> u<0,9>;
default_random_engine e(323);//指定初始化的种子
Standard operations for generating random numbers
#include <iostream>
#include <random>
#include<ctime>
using namespace std;
int main( ){
default_random_engine e;
cout<<time(NULL)<<endl;
e.seed(time(NULL));
uniform_int_distribution<unsigned> u(0, 9);
for(int i=0; i<10; ++i)
cout<<u(e)<<endl;
return 0;
}
1.2 Random distribution engine
C++ provides 16 random number engines.
- default_random_engine
1.3 Random distribution type
C++ provides five types of random distributions
- uniform_int_distribution (up_bound, down_bound) Uniform integer distribution T: short int long long long. Specifies the maximum and minimum values for the uniform distribution.
- uniform_real_distribution (up_bound, down_bound) Uniform floating-point number distribution T: float double. Specify the maximum and minimum values of the uniform distribution
1.4 Method of C
rand()
rand()%100//在100中产生随机数， 但是因为没有随机种子所以，下一次运行也是这个数，因此就要引出srand
srand()
srand((int)time(0)); // 产生随机种子把0换成NULL也行
2 plural
common operation
value access
Arithmetic
Input and output operations
transcendental function
3 Global Numeric Functions
head File
#include<cmath>
#include<cstdlib>
Numeric function
