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1 ## Copyright (C) 2007 David Bateman |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} quiver (@var{u}, @var{v}) |
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21 ## @deftypefnx {Function File} {} quiver (@var{x}, @var{y}, @var{u}, @var{v}) |
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22 ## @deftypefnx {Function File} {} quiver (@dots{}, @var{s}) |
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23 ## @deftypefnx {Function File} {} quiver (@dots{}, @var{style}) |
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24 ## @deftypefnx {Function File} {} quiver (@dots{}, 'filled') |
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25 ## @deftypefnx {Function File} {} quiver (@var{h}, @dots{}) |
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26 ## @deftypefnx {Function File} {@var{h} =} quiver (@dots{}) |
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27 ## |
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28 ## Plot the @code{(@var{u}, @var{v})} components of a vector field in |
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29 ## an @code{(@var{x}, @var{y})} meshgrid. If the grid is uniform, you can |
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30 ## specify @var{x} and @var{y} as vectors. |
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31 ## |
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32 ## If @var{x} and @var{y} are undefined they are assumed to be |
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33 ## @code{(1:@var{m}, 1:@var{n})} where @code{[@var{m}, @var{n}] = |
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34 ## size(@var{u})}. |
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35 ## |
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36 ## The variable @var{s} is a scalar defining a scaling factor to use for |
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37 ## the arrows of the field relative to the mesh spacing. A value of 0 |
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38 ## disables all scaling. The default value is 1. |
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39 ## |
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40 ## The style to use for the plot can be defined with a line style @var{style} |
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41 ## in a similar manner to the line styles used with the @code{plot} command. |
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42 ## If a marker is specified then markers at the grid points of the vectors are |
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43 ## printed rather than arrows. If the argument 'filled' is given then the |
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44 ## markers as filled. |
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45 ## |
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46 ## The optional return value @var{h} provides a list of handles to the |
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47 ## the parts of the vector field (body, arrow and marker). |
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48 ## |
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49 ## @example |
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50 ## @group |
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51 ## [x, y] = meshgrid (1:2:20); |
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52 ## quiver (x, y, sin (2*pi*x/10), sin (2*pi*y/10)); |
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53 ## @end group |
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54 ## @end example |
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55 ## |
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56 ## @seealso{plot} |
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57 ## @end deftypefn |
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58 |
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59 function retval = quiver (varargin) |
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60 |
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61 if (nargin < 2) |
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62 print_usage (); |
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63 elseif (isscalar (varargin{1}) && ishandle (varargin{1})) |
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64 h = varargin {1}; |
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65 if (! strcmp (get (h, "type"), "axes")) |
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66 error ("quiver: expecting first argument to be an axes object"); |
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67 endif |
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68 oldh = gca (); |
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69 unwind_protect |
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70 axes (h); |
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71 newplot (); |
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72 tmp = __quiver__ (h, varargin{2:end}); |
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73 unwind_protect_cleanup |
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74 axes (oldh); |
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75 end_unwind_protect |
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76 else |
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77 newplot (); |
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78 tmp = __quiver__ (gca (), varargin{:}); |
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79 endif |
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80 |
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81 if (nargout > 0) |
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82 retval = tmp; |
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83 endif |
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84 |
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85 endfunction |
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86 |
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87 function hlist = __quiver__ (varargin) |
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88 h = varargin {1}; |
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89 |
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90 s = 1; |
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91 arrowsize = 0.33; |
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92 |
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93 firstnonnumeric = Inf; |
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94 for i = 2:nargin |
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95 if (! isnumeric (varargin {i})) |
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96 firstnonnumeric = i; |
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97 break; |
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98 endif |
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99 endfor |
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100 |
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101 if (nargin < 5 || firstnonnumeric < 5) |
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102 u = varargin{2}; |
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103 v = varargin{3}; |
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104 if (nargin == 4 && isnumeric (varargin{4}) && isscalar (varargin{4})) |
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105 s = varargin{4}; |
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106 iarg = 5; |
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107 else |
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108 iarg = 4; |
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109 endif |
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110 [x, y] = meshgrid (1:size(u,1), 1:size(u,2)); |
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111 else |
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112 x = varargin{2}; |
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113 y = varargin{3}; |
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114 u = varargin{4}; |
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115 v = varargin{5}; |
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116 if (isvector(x) && isvector(y) && (!isvector (u) || !isvector (v))) |
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117 [x, y] = meshgrid (x, y); |
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118 endif |
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119 if (nargin > 5 && isnumeric (varargin{6}) && isscalar (varargin{6})) |
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120 s = varargin{6}; |
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121 iarg = 7; |
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122 else |
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123 iarg = 6; |
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124 endif |
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125 endif |
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126 |
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127 have_filled = false; |
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128 have_line_spec = false; |
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129 while (iarg <= nargin) |
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130 arg = varargin {iarg++}; |
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131 if (ischar (arg) && strncmp (tolower (arg), "filled", 6)) |
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132 have_filled = true; |
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133 elseif ((isstr (arg) || iscell (arg)) |
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134 && ! have_line_spec) |
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135 [linespec, valid] = __pltopt__ ("quiver", arg, false); |
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136 if (valid) |
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137 have_line_spec = true; |
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138 if (strncmp (linespec.linestyle, "none", 4)) |
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139 linespec.linestyle = "-"; |
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140 endif |
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141 else |
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142 error ("quiver: invalid linespec"); |
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143 endif |
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144 else |
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145 error ("quiver: unrecognized argument"); |
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146 endif |
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147 endwhile |
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148 |
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149 if (s) |
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150 ## Scale the arrows to fit in the grid |
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151 dx = (max(x(:)) - min(x(:))) ./ size (x, 2); |
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152 dy = (max(y(:)) - min(y(:))) ./ size (y, 1); |
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153 len = max (sqrt (u(:).^2 + dy(:).^2)); |
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154 if (len > 0) |
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155 s = s / sqrt (2) * sqrt (dx.^2 + dy.^2) / len; |
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156 u = s * u; |
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157 v = s * v; |
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158 endif |
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159 endif |
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160 |
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161 x = x(:); |
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162 y = y(:); |
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163 xend = x + u(:); |
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164 yend = y + v(:); |
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165 |
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166 hstate = get (h, "nextplot"); |
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167 unwind_protect |
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168 if (have_line_spec) |
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169 h1 = plot ([x.'; xend.'; NaN(1, length (x))](:), |
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170 [y.'; yend.'; NaN(1, length (y))](:), |
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171 "linestyle", linespec.linestyle); |
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172 else |
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173 h1 = plot ([x.'; xend.'; NaN(1, length (x))](:), |
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174 [y.'; yend.'; NaN(1, length (y))](:)); |
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175 endif |
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176 hold on; |
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177 |
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178 xtmp = x + u(:) .* (1 - arrowsize); |
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179 ytmp = y + v(:) .* (1 - arrowsize); |
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180 xarrw1 = xtmp + (y - yend) * arrowsize / 3; |
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181 xarrw2 = xtmp - (y - yend) * arrowsize / 3; |
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182 yarrw1 = ytmp - (x - xend) * arrowsize / 3; |
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183 yarrw2 = ytmp + (x - xend) * arrowsize / 3; |
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184 |
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185 if (have_line_spec) |
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186 if (isfield (linespec, "marker") && |
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187 ! strncmp (linespec.marker, "none", 4)) |
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188 h2 = plot ([xarrw1.'; xend.'; xarrw2.'; NaN(1, length (x))](:), |
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189 [yarrw1.'; yend.'; yarrw2.'; NaN(1, length (y))](:), |
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190 "linestyle", "none"); |
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191 else |
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192 h2 = plot ([xarrw1.'; xend.'; xarrw2.'; NaN(1, length (x))](:), |
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193 [yarrw1.'; yend.'; yarrw2.'; NaN(1, length (y))](:), |
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194 "linestyle", linespec.linestyle); |
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195 endif |
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196 else |
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197 h2 = plot ([xarrw1.'; xend.'; xarrw2.'; NaN(1, length (x))](:), |
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198 [yarrw1.'; yend.'; yarrw2.'; NaN(1, length (y))](:)); |
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199 endif |
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200 |
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201 if (! have_line_spec || (isfield (linespec, "marker") && |
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202 strncmp (linespec.marker, "none", 4))) |
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203 h3 = plot (x, y, "linestyle", "none", "marker", "none"); |
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204 else |
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205 h3 = plot (x, y, "linestyle", "none", "marker", linespec.marker); |
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206 endif |
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207 if (have_filled) |
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208 ## FIXME gnuplot doesn't respect the markerfacecolor field |
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209 set(h3, "markerfacecolor", get (h1, "color")); |
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210 endif |
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211 unwind_protect_cleanup |
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212 set (h, "nextplot", hstate); |
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213 end_unwind_protect |
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214 |
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215 hlist = [h1; h2; h3]; |
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216 |
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217 endfunction |
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218 |
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219 %!demo |
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220 %! [x,y] = meshgrid(1:2:20); |
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221 %! quiver(x,y,sin(2*pi*x/10),sin(2*pi*y/10)) |
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222 |
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223 %!demo |
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224 %! axis("equal"); |
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225 %! x=linspace(0,3,80); y=sin(2*pi*x); theta=2*pi*x+pi/2; |
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226 %! quiver(x,y,sin(theta)/10,cos(theta)/10); |
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227 %! hold on; plot(x,y,"r"); hold off; |
