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1 ## Copyright (C) 2000 John W. Eaton |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify it |
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4 ## under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this program; see the file COPYING. If not, write to the Free |
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15 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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16 ## 02111-1307, USA. |
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17 |
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18 ## usage: quiver (x, y, u, v) |
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19 ## usage: quiver (u, v) |
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20 ## |
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21 ## Plot the (u,v) components of a vector field in a (x,y) meshgrid. |
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22 ## |
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23 ## You can try: |
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24 ## |
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25 ## a = b = 1:10; |
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26 ## [x,y] = meshgrid(a,b); |
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27 ## u = rand (10,10); |
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28 ## v = rand (10,10); |
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29 ## quiver(x,y,u,v) |
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30 ## |
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31 ## See also: plot, semilogx, semilogy, loglog, polar, mesh, contour, |
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32 ## bar, stairs, gplot, gsplot, replot, xlabel, ylabel, title |
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33 |
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34 ## Author: Roberto A. F. Almeida (roberto@calvin.ocfis.furg.br) |
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35 ## 2001-02-25 Paul Kienzle |
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36 ## * change parameter order to correspond to matlab |
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37 ## * allow vector x,y, defaulting to 1:n, 1:m for mxn u |
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38 ## * vectorize |
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39 |
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40 ## TODO: use gnuplot 'vector' style instead of setting arrows one at a time |
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41 function quiver (x, y, u, v) |
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42 |
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43 if (nargin != 2 && nargin != 4) |
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44 usage ("quiver (x, y, u, v)"); |
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45 endif |
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46 |
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47 if (nargin == 2) |
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48 u = x; v = y; x = 1:columns(u); y= 1:rows(u); |
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49 endif |
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50 |
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51 if (any(size(u)!=size(v))) |
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52 error ("quiver: u, v must have the same shape."); |
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53 endif |
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54 |
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55 if is_vector(x) && is_vector(y) |
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56 [nr, nc] = size(u); |
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57 if (length(x) != nc || length(y) != nr) |
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58 error ("quiver: x, y vectors must have correct length"); |
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59 endif |
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60 [x,y] = meshgrid(x,y); |
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61 endif |
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62 |
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63 if (any (size(x) != size(u) | size(y) != size(u))) |
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64 error ("quiver: x, y must have the same shape as u, v"); |
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65 endif |
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66 |
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67 |
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68 ## Calculating the grid limits. |
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69 |
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70 minx = min (min (x)); |
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71 maxx = max (max (x)); |
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72 miny = min (min (y)); |
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73 maxy = max (max (y)); |
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74 |
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75 max_arrow = max ( [max(max (u)) , max(max (v)) , ... |
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76 abs(min (min (u))) , abs(min (min (v)))] ); |
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77 border = max_arrow * 1.2; |
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78 |
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79 limits = [ minx - border, maxx + border, miny - border, maxy + border ]; |
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80 |
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81 axis (limits); |
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82 |
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83 |
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84 ## Ok, now plot the arrows. |
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85 |
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86 gset noarrow; |
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87 gplot 0 title ""; |
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88 |
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89 command = sprintf ("gset arrow from %f,%f to %f,%f\n", \ |
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90 [ x(:)'; y(:)'; x(:)'+u(:)'; y(:)'+v(:)' ]); |
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91 eval ( [ "if 1\n", command, "\nendif" ] ); |
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92 |
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93 replot; |
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94 |
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95 endfunction |
