c语言直线和椭圆的交点,直线与椭圆相交求交点

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c语言直线和椭圆的交点,直线与椭圆相交求交点

#include

#include

#include

void main()

{

double a,b,c,x1,x2,y1,y2,k,j;

printf("\nplease input a,b:\n");

scanf("%lf%lf",&a,&b);

printf("\nplease input x1,y1,x2,y2\n");

scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);

k=(y1-y2)/(x1-x2);

c=y1-k*x1;

j=(2*a*a*k*c)*(2*a*a*k*c)-4*(b*b+a*a*k*k)*a*a*(c*c-b*b);

if(j<0)

printf("\nthe line don't intersect with the ellipse");

else

if(j==0)

{

x1=-2*k*c*a*a/(2*(b*b+a*a*k*k));

y1=k*x1+c;

printf("\nthe line and ellipse intersect at\n(%lf,%lf)",x1,y1);

}

else

{

x1=(-2*k*c*a*a+sqrt(j))/(2*(b*b+a*a*k*k));

y1=k*x1+c;

x2=(-2*k*c*a*a-sqrt(j))/(2*(b*b+a*a*k*k));

y2=k*x2+c;

printf("\nthe line and ellipse intersect at\n(%lf,%lf) and (%lf,%lf)",x1,y1,x2,y2);

}

getch();

}