user1307376 - 4 months ago 21

C# Question

I have two points (x1,y1) and (x2,y2). I want to know whether the points are within 5 meters of one another.

Answer

measure the square distance from one point to the other:

```
((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)) < d*d
```

where d is the distance, (x1,y1) are the coordinates of the 'base point' and (x2,y2) the coordinates of the point you want to check.

or if you prefer:

```
(Math.Pow(x1-x2,2)+Math.Pow(y1-y2,2)) < (d*d);
```

Noticed that the preferred one does not call Pow at all for speed reasons, and the second one, probably slower, as well does not call `Math.Sqrt`

, always for performance reasons. Maybe such optimization are premature in your case, but they are useful if that code has to be executed a lot of times.

Of course you are talking in meters and I supposed point coordinates are expressed in meters too.