Re: vector question

From: NCAR G Talk (ncargt AT unknown)
Date: Thu Dec 21 1995 - 09:05:23 MST


>
> Greetings.
>
> A question regarding VVECTR:
>
> Assuming the grid is uniformly spaced, and, unless otherwise set using the "MAP"
> option, shouldn't the vectors be plotted such that their starting positions
> are also uniformly spaced? I've found this _not_ to be true in one of my plots,
> as a few (typically large) vectors have starting positions anomalously close to a neighbor. This problem did not occur when I used the antiquated VELVCT.
>
> Have any of you ever encountered this, and if so, have you also found a fix?
>
> Thanks in advance,
>
> Jeff
>

Jeff,

The difference, rightly or wrongly, is simply that the current Vectors
package has a different default value for the vector positioning
parameter. This parameter ('VPO' in Vectors) allows one to set the
arrow head, center, or tail to the grid location. The default for
Vectors is 'center', whereas VELVCT set it to 'tail'. In order to make
Vectors work like VELVCT in this respect, simply include the following
line in your code (any time before the VVECTR call):

        CALL VVSETI('VPO',1)

--NCAR Graphics Support



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