Re: Problem with finding angles between points in Cartesian plane
- To: mathgroup at smc.vnet.net
- Subject: [mg26140] Re: Problem with finding angles between points in Cartesian plane
- From: adam_smith at my-deja.com
- Date: Tue, 28 Nov 2000 01:56:39 -0500 (EST)
- References: <email@example.com>
- Sender: owner-wri-mathgroup at wolfram.com
Derek, Try the alternate version of ArcTan, ArcTan[x,y]. See Help under ArcTan. In:= x1 = 3; y1 = 4; x2 = 3; y2 = 6; (180/Pi)*ArcTan[(x2 - x1), (y2 - y1)] (180/Pi)*ArcTan[(x1 - x2), (y1 - y2)] Out= 90 Out= -90 Adam Smith In article <8vfqv9$jif at smc.vnet.net>, "Blitzer" <drek1976 at yahoo.com> wrote: > I would like to find the angle between 2 points on the Cartesian plane. > However, if I use "ArcTan", it is not able to recognise that points with the > same x-coordinates have an angle of 90 degrees between them. It returns > "Indeterminate". > eg. for a point A (x1, y1) and a point (x1, y2), to find the angle between > them, I use ArcTan[(y2-y1)/(x1-x1)]. However, as the denominator is equal to > "0", this function returns "indeterminate". Is there a way to get around > this problem? Or is there other possible functions which can be used. > I am dealing with a very large array of numbers and thus, it's not possible > to check the coordinates individually. > > Would be grateful for any help rendered. Thanks! > > Derek > > Sent via Deja.com http://www.deja.com/ Before you buy.