Re: [Plplot-devel] Vector plot in curve coordinate

 Re: [Plplot-devel] Vector plot in curve coordinate From: Andrew Ross - 2007-12-10 14:41:48 ```On Mon, Dec 10, 2007 at 11:11:42PM +0900, Hiroyasu Yasuda wrote: > > On 2007/12/10, at 17:53, Arjen Markus wrote: > > >> Dear all: > >> > >> I would like to plot vectors in general curve coordinate as attached > >> picture. Of course I have already try to be plotting with plvec2. > >> When I gave the vector data which is u =1.0 and v=0.0, the plotted > >> vectors look like along co-orthogonal coordinate. > >> > >> I think that plplot has the vector plotting function in general curve > >> coordinate because I read the reference of plplot and sample code of > >> x22f. Can we plot that things? > >> > > Hello Arjen: > > > that means that the components of the vector are not cartesian > > but based on the (local) coordinate system (or grid orientation)? > > Yes, that is, I have been computing with local coordinate system. > > > That means that PLplot will have to keep track of this more general > > coordinate system. Isn't it simpler to convert the components from > > the curve coordinate system to the cartesian plotting coordinates? > > When I'm computing and then plot the vectors with local coordinate > system, do we have to convert the vector component to plot the > vectors along local coordinate under plplot? Hiro, Although you can specify non-cartesian coordinates to plot vectors at, for example using pltr2 as in the last plot of example 22, this only specifies the location of the vectors. The vector components are always assumed to be cartesian. As Arjen said, if you want to use local coordinates for the vector components, you need to convert them to cartesian cordinates before plotting. Andrew ```