二维平面几何

二维平面几何中关于向量运算的实现

#include <iostream>#include<cmath>using namespace std;/* run this program using the console pauser or add your own getch, system("pause") or input loop */struct point{    double x,y;    point(double x=0,double y=0):x(x),y(y){}};typedef point Vector;Vector operator+(Vector a,Vector b){    return Vector(a.x+b.x,a.y+b.y);}Vector operator-(Vector a,Vector b){    return Vector(a.x-b.x,a.y-b.y);}Vector operator*(Vector a,double p){    return Vector(a.x*p,a.y*p);}Vector operator/(Vector a,double p){    return Vector(a.x/p,a.y/p);}bool operator <(const point&a,const point&b){    return a.x<b.x||(a.x==b.x&&a.y<b.y);}const double eps=1e-10;int dcmp(double x){    if(fabs(x)<eps)return 0;    else return x<0?-1:1;}bool operator ==(const point&a,const point&b){    return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0;}double Dot(Vector a,Vector b){    return a.x*b.x+a.y*b.y;}double Length(Vector a){    return sqrt(Dot(a,a));}double Angle(Vector a,Vector b){    return acos(Dot(a,b)/Length(a)/Length(b));}double Cross(Vector a,Vector b){    return a.x*b.y-a.y-b.x;}double Area2(point a,point b,point c){    return Cross(b-a,c-a);}Vector Rotate(Vector a,double rad){    return Vector(a.x*cos(rad)-a.y*sin(rad),a.x*sin(rad)+a.y*cos(rad));}point Getlineintersection(point p,Vector v,point q,Vector w){//两条直线交点     Vector u=p-q;    double t=Cross(w,u)/Cross(v,w);    return p+v*t;}double distancetoline(point p,point a,point b){    Vector v1=b-a,v2=p-a;    return fabs(Cross(v1,v2))/Length(v1);}int main(int argc, char** argv) {    return 0;}