Расстояние от точки до луча (описание внутри)

#include <iostream>
#include <vector>
#include <limits>
#include <string>
#include <algorithm>
 
using namespace std;
 
double dist_point_point(double x1, double y1, double x2, double y2) {
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
 
double dist_point_line(double x, double y, double x1, double y1, double x2, double y2) {
    double det = abs((y1 - y2) * (x1 - x) - (x1 - x2) * (y1 - y));
    x1 -= x2; y1 -= y2;
    det /= sqrt(x1 * x1 + y1 * y1);
    return det;
}
 
bool comp(double x, double y) {
    return (abs(x - y) <= 1e-9);
}
 
bool inRay(double x, double y, double x1, double y1, double x2, double y2) {
    // x, y must be in line with ray
    double kx1 = x2 - x1;
    double ky1 = y2 - y1;
    double d = dist_point_point(x1, y1, x2, y2);
    kx1 /= d;
    ky1 /= d;
    double kx2 = x - x1;
    double ky2 = y - y1;
    double d2 = dist_point_point(x1, y1, x, y);
    kx2 /= d2;
    ky2 /= d2;
    return (comp(kx1, kx2) && comp(ky1, ky2));
}
 
double dist_point_ray(double x, double y, double x1, double y1, double x2, double y2) {
    double dpl = dist_point_line(x, y, x1, y1, x2, y2);
    double A = y2 - y1;
    double B = x1 - x2;
    double cf = sqrt(A*A + B*B);
    A /= cf; // Normalize
    B /= cf; // Normalize
    double xp1 = x + A * dpl;
    double yp1 = y + B * dpl;
    double xp2 = x - A * dpl;
    double yp2 = y - B * dpl;
    double dpl1 = dist_point_line(xp1, yp1, x1, y1, x2, y2);
    double dpl2 = dist_point_line(xp2, yp2, x1, y1, x2, y2);
    if (dpl2 < dpl1) {
        swap(xp1, xp2);
        swap(yp1, yp2);
    }
    if (inRay(xp1, yp1, x1, y1, x2, y2))
        return dpl;
    else
        return min(dist_point_point(x, y, x1, y1), dist_point_point(x, y, x2, y2));
}
 
int main(){    
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);
    double x, y, x1, y1, x2, y2;
    scanf("%lf%lf%lf%lf%lf%lf", &x, &y, &x1, &y1, &x2, &y2);
    printf("%.15lf", dist_point_ray(x, y, x1, y1, x2, y2));
    return 0;
}