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view main/plot/quiver.m @ 0:6b33357c7561 octave-forge
Initial revision
author | pkienzle |
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date | Wed, 10 Oct 2001 19:54:49 +0000 |
parents | |
children | 2ac2777b30bc |
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## Copyright (C) 2000 John W. Eaton ## ## This program is free software; you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 2, or (at your option) ## any later version. ## ## This program is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ## General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this program; see the file COPYING. If not, write to the Free ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA ## 02111-1307, USA. ## usage: quiver (x, y, u, v) ## usage: quiver (u, v) ## ## Plot the (u,v) components of a vector field in a (x,y) meshgrid. ## ## You can try: ## ## a = b = 1:10; ## [x,y] = meshgrid(a,b); ## u = rand (10,10); ## v = rand (10,10); ## quiver(x,y,u,v) ## ## See also: plot, semilogx, semilogy, loglog, polar, mesh, contour, ## bar, stairs, gplot, gsplot, replot, xlabel, ylabel, title ## Author: Roberto A. F. Almeida (roberto@calvin.ocfis.furg.br) ## 2001-02-25 Paul Kienzle ## * change parameter order to correspond to matlab ## * allow vector x,y, defaulting to 1:n, 1:m for mxn u ## * vectorize ## TODO: use gnuplot 'vector' style instead of setting arrows one at a time function quiver (x, y, u, v) if (nargin != 2 && nargin != 4) usage ("quiver (x, y, u, v)"); endif if (nargin == 2) u = x; v = y; x = 1:columns(u); y= 1:rows(u); endif if (any(size(u)!=size(v))) error ("quiver: u, v must have the same shape."); endif if is_vector(x) && is_vector(y) [nr, nc] = size(u); if (length(x) != nc || length(y) != nr) error ("quiver: x, y vectors must have correct length"); endif [x,y] = meshgrid(x,y); endif if (any (size(x) != size(u) | size(y) != size(u))) error ("quiver: x, y must have the same shape as u, v"); endif ## Calculating the grid limits. minx = min (min (x)); maxx = max (max (x)); miny = min (min (y)); maxy = max (max (y)); max_arrow = max ( [max(max (u)) , max(max (v)) , ... abs(min (min (u))) , abs(min (min (v)))] ); border = max_arrow * 1.2; limits = [ minx - border, maxx + border, miny - border, maxy + border ]; axis (limits); ## Ok, now plot the arrows. gset noarrow; gplot 0 title ""; command = sprintf ("gset arrow from %f,%f to %f,%f\n", \ [ x(:)'; y(:)'; x(:)'+u(:)'; y(:)'+v(:)' ]); eval ( [ "if 1\n", command, "\nendif" ] ); replot; endfunction