[59] | 1 | ;+ |
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| 2 | ; NAME: cutpar |
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| 3 | ; |
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| 4 | ; PURPOSE: cut p parallelogram(s) into p*n^2 parallelograms |
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| 5 | ; |
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| 6 | ; CATEGORY: basic work |
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| 7 | ; |
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| 8 | ; CALLING SEQUENCE:res = cutpar(x0, y0, x1, y1, x2, y2, x3, y3, n) |
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| 9 | ; |
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| 10 | ; INPUTS: |
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| 11 | ; x0,y0 1d arrays of p elements, giving the edge positions. The |
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| 12 | ; edges must be given as in plot to traw the parallelogram. (see |
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| 13 | ; example). |
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| 14 | ; n: each parallelogram will be cutted in n^2 pieces |
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| 15 | ; |
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| 16 | ; KEYWORD PARAMETERS: |
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| 17 | ; |
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| 18 | ; /endpoints: see outputs |
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| 19 | ; |
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| 20 | ; /onsphere: to specify that the points are located on a |
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| 21 | ; sphere. In this case, x and y corresponds to longitude and |
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| 22 | ; latitude in degrees. |
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| 23 | ; |
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| 24 | ; OUTPUTS: |
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| 25 | ; -defaut: 3d array(2,n^2,p) giving the center position of each |
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| 26 | ; piece of the parallelograms |
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| 27 | ; -/endpoints: 3d array(2,(n+1)^2,p) giving the edge positions |
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| 28 | ; of each piece of the parallelograms |
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| 29 | ; |
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| 30 | ; COMMON BLOCKS: no |
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| 31 | ; |
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| 32 | ; SIDE EFFECTS: need cutsegment.pro |
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| 33 | ; |
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| 34 | ; RESTRICTIONS: ? |
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| 35 | ; |
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| 36 | ; EXAMPLE: |
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| 37 | ; |
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| 38 | ; x0 = [2,6,2] |
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| 39 | ; y0 = [0,2,6] |
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| 40 | ; x1 = [3,8,4] |
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| 41 | ; y1 = [4,4,6] |
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| 42 | ; x2 = [1,6,4] |
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| 43 | ; y2 = [5,6,8] |
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| 44 | ; x3 = [0,4,2] |
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| 45 | ; y3 = [1,4,8] |
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| 46 | ; n = 4 |
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| 47 | ; splot, [0,10], [0,10], xstyle = 1, ystyle = 1,/nodata |
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| 48 | ; for i=0,2 do oplot, [x0[i],x1[i],x2[i],x3[i],x0[i]],[y0[i],y1[i],y2[i],y3[i],y0[i]] |
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| 49 | ; res=cutpar(x0, y0, x1, y1, x2, y2, x3, y3, n) |
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| 50 | ; for i=0,2 do oplot, [res[0,*,i]], [res[1,*,i]], color = 20+10*i, psym = 1, thick = 3 |
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| 51 | ; |
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| 52 | ; MODIFICATION HISTORY: |
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| 53 | ; S. Masson (smasson@lodyc.jussieu.fr) |
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| 54 | ; July 5th, 2002 |
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| 55 | ;- |
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| 56 | FUNCTION cutpar, x0, y0, x1, y1, x2, y2, x3, y3, n, endpoints = endpoints, onsphere = onsphere |
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| 57 | ; is it a parallelogram? |
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| 58 | ; eps = 1e-4 |
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| 59 | ; IF total(abs((x0+x2)/2-(x1+x3)/2) GE eps) GT 0 $ |
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| 60 | ; OR total(abs((y0+y2)/2-(y1+y3)/2) GE eps) GT 0 $ |
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| 61 | ; THEN stop; print, 'NOT a parallelogram' |
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| 62 | ; x0(npar) |
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| 63 | npar = n_elements(x0) |
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| 64 | ; firstborder(2,n+keyword_set(endpoints),npar) |
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| 65 | firstborder = cutsegment(x0, y0, x1, y1, n $ |
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| 66 | , endpoints = endpoints, onsphere = onsphere) |
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| 67 | thirdborder = cutsegment(x3, y3, x2, y2, n $ |
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| 68 | , endpoints = endpoints, onsphere = onsphere) |
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| 69 | ; res(2,n+keyword_set(endpoints),(n+keyword_set(endpoints))*npar) |
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| 70 | res = cutsegment(firstborder[0, *, *], firstborder[1, *, *] $ |
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| 71 | , thirdborder[0, *, *], thirdborder[1, *, *] $ |
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| 72 | , n, endpoints = endpoints, onsphere = onsphere) |
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| 73 | ; free memory |
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| 74 | firstborder = -1 |
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| 75 | thirdborder = -1 |
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| 76 | ; reform the result |
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| 77 | res = reform(res, 2, (n+keyword_set(endpoints))^2, npar, /overwrite) |
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| 78 | |
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| 79 | RETURN, res |
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| 80 | END |
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