Splitting Wind direction into four quadrants

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Student new 2016-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/263926-splitting-wind-direction-into-four-quadrants

评论： Student new 2016-1-15

采纳的回答： Chad Greene

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Hello,

I had u & V component of wind. I converted them to wind speed & direction, using

 wind_speed=sqrt((u^2)+(v^2));
 wind_direction=180 + atand(u/v);

The problem is wind direction is not splitting into quadrants. As done here http://wx.gmu.edu/dev/clim301/lectures/wind/wind-uv.html

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Answer 1

Chad Greene 2016-1-15

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I think Kelly is partly correct. You'll need the four-quadrant version of atand, which is called atan2d.

Another quick tip: Instead of this:

wind_speed=sqrt((u^2)+(v^2));

you can use

wind_speed=hypot(u,v);

which is less prone to typos.

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Student new 2016-1-15

编辑：Student new 2016-1-15

Thanks alot Star Strider, you made my day..

You are right i was doing a mistake of (/). But i can not see comment of Star strider now..

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Answer 2

Kelly Kearney 2016-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/263926-splitting-wind-direction-into-four-quadrants#answer_206309

As mentioned in those lecture notes, you'll need to use atan2 instead of atan (not atand either... your inputs aren't in degrees!) to get the four-quadrant result you want.

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Kelly Kearney 2016-1-15

Right, never mind on the degrees comment. I was mistakenly reversing inputs and outputs in my head. But as Chad answered, you still need the atan2d variant.

Student new 2016-1-15