<div>Dear Amjad</div>
<div> Is it atan2(u,v).........or atan2(v,u)..............</div>
<div> I hope it's atan2(v,u)........</div>
<div> </div>
<div>regards</div>
<div>dipak<br><br></div>
<div class="gmail_quote">On Thu, Nov 12, 2009 at 5:46 PM, Muhammad Amjad <span dir="ltr"><<a href="mailto:amjadozi@gmail.com">amjadozi@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Dear Chris,<br><br>Could you please check with the following formula:<br>wdir=atan2(u,v)/0.01745329 +180<br>
The size of wind represents the wind speed. So, I don't think the dispariy among the vectors can be removed.<br><br>Cheers,<br><font color="#888888">Amjad.</font>
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<div class="h5"><br><br><br>
<div><span class="gmail_quote">On 11/9/09, <b class="gmail_sendername">Chris Hayes</b> <<a href="mailto:c.hayes@weeronline.nl" target="_blank">c.hayes@weeronline.nl</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">
<div text="#000000" bgcolor="#ffffff"><font face="Arial">dear group,<br><br>I need to plot the wind directions for stations with equally sized arrows.<br><br>My dataset contains the direction in degrees (0-360).<br><br>I use the gxout=vector map which requires a u and a v vector component (i.e. the vertical and horizontal vector component).<br>
<br>u<br>| /winddir<br>| /<br>| /<br>|/___ v<br><br><br>I calculate u as -sin(winddir * pi/180)<br></font><font face="Arial">I calculate v as -cos(winddir * pi/180)<br></font><br><font face="Arial">resulting in the display-command ' -8*(sin(winddir * 0.0175)) ; -8*(cos(</font><font face="Arial">winddir</font><font face="Arial"> * 0.0175)) '<br>
(where 8 makes the size of the arrow, which usually represents windspeed but here is desired to be constant)<br><br><br>The direction of the arrows looks fine. <br>But some maps have only tiny arrows and some maps have only longtailed arrows. <br>
I cannot see a pattern. I have no mixed maps with tiny and large arrows.<br><br>Should I change my formula, or the way I give the display command?<br><br>thanks,<br>Chris <br><br></font><br></div></blockquote></div><br></div>
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