cspice_pltar |
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## AbstractCSPICE_PLTAR computes the total area of a collection of triangular plates. For important details concerning this module's function, please refer to the CSPICE routine pltar_c. ## I/OGiven: vrtces is an array containing the plate model's vertices. Elements vrtces[0,i-1] vrtces[1,i-1] vrtces[2,i-1] are, respectively, the X, Y, and Z components of the ith vertex, where `i' ranges from 1 to m, the number of triangular plates comprising the plate set. This routine doesn't associate units with the vertices. plates is an array containing 3-tuples of integers representing the model's plates. The elements of `plates' are vertex indices. The vertex indices are 1-based: vertices have indices ranging from 1 to n, the number of vertices comprising the plate set. The elements plates[0,i-1] plates[1,i-1] plates[2,i-1] are, respectively, the indices of the vertices comprising the ith plate. Note that the order of the vertices of a plate is significant: the vertices must be ordered in the positive (counterclockwise) sense with respect to the outward normal direction associated with the plate. In other words, if v1, v2, v3 are the vertices of a plate, then ( v2 - v1 ) x ( v3 - v2 ) points in the outward normal direction. Here "x" denotes the vector cross product operator. the call: double = CSPICE_PLTAR( vrtces, plates ) returns: pltar The function returns the total area of the input set of plates. Each plate contributes the area of the triangle defined by the plate's vertices. If the components of the vertex array have length unit L, then the output area has units 2 L ## ExamplesAny numerical results shown for this example may differ between platforms as the results depend on the SPICE kernels used as input and the machine specific arithmetic implementation. Compute the area of the pyramid defined by the four triangular plates whose vertices are the 3-element subsets of the set of vectors: ( 0, 0, 0 ) ( 1, 0, 0 ) ( 0, 1, 0 ) ( 0, 0, 1 ) PRO PLTAR_T ;; ;; Let the notation ;; ;; < A, B > ;; ;; denote the dot product of vectors A and B. ;; ;; The plates defined below lie in the following planes, ;; respectively: ;; ;; Plate 1: { P : < P, (-1, 0, 0) > = 0 } ;; Plate 2: { P : < P, ( 0, -1, 0) > = 0 } ;; Plate 3: { P : < P, ( 0, 0, -1) > = 0 } ;; Plate 4: { P : < P, ( 1, 1, 1) > = 1 } ;; vrtces =[ [ 0.D, 0.0, 0.0 ], $ [ 1.D, 0.0, 0.0 ], $ [ 0.D, 1.0, 0.0 ], $ [ 0.D, 0.0, 1.0 ] ] plates =[ [ 1L, 4, 3 ], $ [ 1, 2, 4 ], $ [ 1, 3, 2 ], $ [ 2, 3, 4 ] ] area = ## ParticularsThis routine computes the total area of a set of triangular plates. The plates need not define a closed surface. Examples of valid plate sets: Tetrahedron Box Tiled ellipsoid Tiled ellipsoid with one plate removed Two disjoint boxes Two boxes with intersection having positive volume Single plate Empty plate set ## Required ReadingICY.REQ DSK.REQ ## Version-Icy Version 1.0.0, 15-DEC-2016, ML (JPL), EDW (JPL) ## Index_Entriescompute plate model area |

Wed Apr 5 17:58:02 2017