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7018
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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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6721
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19 function interpimages (nm, typ) |
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20 bury_output (); |
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21 if (strcmp (nm, "interpft")) |
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22 t = 0 : 0.3 : pi; dt = t(2)-t(1); |
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23 n = length (t); k = 100; |
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24 ti = t(1) + [0 : k-1]*dt*n/k; |
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25 y = sin (4*t + 0.3) .* cos (3*t - 0.1); |
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26 yp = sin (4*ti + 0.3) .* cos (3*ti - 0.1); |
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27 plot (ti, yp, 'g', ti, interp1(t, y, ti, 'spline'), 'b', ... |
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28 ti, interpft (y, k), 'c', t, y, 'r+'); |
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29 legend ('sin(4t+0.3)cos(3t-0.1','spline','interpft','data'); |
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30 print (strcat (nm, ".", typ), strcat ("-d", typ)) |
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31 elseif (strcmp (nm, "interpn")) |
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32 x = y = z = -1:1; |
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33 f = @(x,y,z) x.^2 - y - z.^2; |
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34 [xx, yy, zz] = meshgrid (x, y, z); |
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35 v = f (xx,yy,zz); |
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36 xi = yi = zi = -1:0.1:1; |
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37 [xxi, yyi, zzi] = ndgrid (xi, yi, zi); |
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38 vi = interpn(x, y, z, v, xxi, yyi, zzi, 'spline'); |
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6723
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39 mesh (zi, yi, squeeze (vi(1,:,:))); |
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6721
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40 print (strcat (nm, ".", typ), strcat ("-d", typ)) |
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6743
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41 elseif (strcmp (nm, "interpderiv1")) |
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42 t = -2:2; |
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43 dt = 1; |
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44 ti =-2:0.025:2; |
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45 dti = 0.025; |
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46 y = sign(t); |
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47 ys = interp1(t,y,ti,'spline'); |
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48 yp = interp1(t,y,ti,'pchip'); |
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49 plot (ti, ys,'r-', ti, yp,'g-'); |
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50 legend('spline','pchip', 4); |
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51 print (strcat (nm, ".", typ), strcat ("-d", typ)) |
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52 elseif (strcmp (nm, "interpderiv2")) |
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53 t = -2:2; |
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54 dt = 1; |
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55 ti =-2:0.025:2; |
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56 dti = 0.025; |
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57 y = sign(t); |
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6721
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58 ddys = diff(diff(interp1(t,y,ti,'spline'))./dti)./dti; |
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59 ddyp = diff(diff(interp1(t,y,ti,'pchip'))./dti)./dti; |
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6743
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60 plot (ti(2:end-1),ddys,'r*', ti(2:end-1),ddyp,'g+'); |
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61 legend('spline','pchip'); |
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6721
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62 print (strcat (nm, ".", typ), strcat ("-d", typ)) |
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63 endif |
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64 bury_output (); |
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65 endfunction |
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66 |
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67 ## Use this function before plotting commands and after every call to |
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68 ## print since print() resets output to stdout (unfortunately, gnpulot |
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69 ## can't pop output as it can the terminal type). |
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70 function bury_output () |
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71 f = figure (1); |
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72 set (f, "visible", "off"); |
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73 endfunction |
