Intersection between line and circle

Question

Selva 2014-7-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/143504-intersection-between-line-and-circle

编辑： Image Analyst 2014-8-21

采纳的回答： Image Analyst

Please check the image above

I need to find the intersection point of the line with the circle 3 and circle 4.

If I use linecirc() command, i get the values of circle 1 also.

Is there any other command to get the required values ?

Thanks in advance

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Answer 1

Image Analyst 2014-7-27

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https://ww2.mathworks.cn/matlabcentral/answers/143504-intersection-between-line-and-circle#answer_146553

编辑：Image Analyst 2014-7-27

Each circle with have either 0, 1, or 2 intersection points. Do you have the formula for each circle, meaning it's center coordinates and radius ? If seems like knowing the formulas for the lines you might be able to use fzero() to find the intersection point(s).

By the way, what toolbox is linecirc() in? I don't have it.

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Image Analyst 2014-7-27

编辑：Image Analyst 2014-7-27

I will add it to the Products list for you. Does that give the 0, 1, or 2 intersection points?

Selva 2014-8-21

编辑：Image Analyst 2014-8-21

2 intersection points if it cuts the circle

2 same points if its a tangent

Nan if its does not intersect with the circle

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Answer 2

Matt J 2014-7-27

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https://ww2.mathworks.cn/matlabcentral/answers/143504-intersection-between-line-and-circle#answer_146551

编辑：Matt J 2014-7-27

Find all points of intersection and write each in the form

P_intersection = P1+t*(P2-P1)

where t is a scalar parameter. Solve for each t by doing

t = (P2-P1)\(P_intersection-P1)

Then discard all intersections other than the ones for which 0<=t<=1. The intersections that remain will all lie on the line segment between P1 and P2.