最有效的方式查找数组中的值。

三角测量三角在二维或三维三角剖分的支持拓扑和几何查询2 d和3 d空间。金宝app例如,您可以查询三角形连接到一个顶点,三角形的邻居信息,外心等等。您可以创建一个三角直接使用现有三角矩阵中的数据格式。或者,您可以创建一个delaunayTriangulation,它提供了对三角函数的访问。TR =三角(三,X, Y)创建一个二维三角从三角连接矩阵三分(X, Y)。三是一个m-by-3矩阵m是三角形的数量。每一行定义一个三角形的三顶点id -点的行数(X, Y)。点坐标(X, Y)代表三角的点列向量。TR =三角(三,X, Y, Z)创建一个3 d三角从三角连接矩阵三分(X, Y, Z)。三是一个m-by-3 m-by-4矩阵表示m三角形或四面体,分别有3或4个顶点。每一行三定义一个三角形或四面体的顶点id -点的行数(X, Y, Z)。点坐标(X, Y, Z)代表三角的点列向量。TR =三角(三,P)创建一个三角的三角连接矩阵三分三页是一个m-by-3 m-by-4矩阵表示m三角形或四面体,分别有3或4个顶点。每一行三定义一个三角形或四面体的顶点id,点P的行数是一个mpts-by-ndim矩阵那些mpt是点的数量和ndim维度的数量,2 < = ndim < = 3。示例1:%加载一个2 d三角矩阵格式和使用三角%查询自由边界边。 load trimesh2d % This loads triangulation tri and vertex coordinates x, y trep = triangulation(tri, x,y); fe = freeBoundary(trep)'; triplot(trep); % Add the free edges in red hold on; plot(x(fe), y(fe), 'r','LineWidth',2); hold off; axis([-50 350 -50 350]); axis equal; Example 2: % Load a 3D tetrahedral triangulation in matrix format and use the % triangulation to compute the free boundary. load tetmesh % This loads triangulation tet and vertex coordinates X trep = triangulation(tet, X); [tri, Xb] = freeBoundary(trep); %Plot the surface mesh trisurf(tri, Xb(:,1), Xb(:,2), Xb(:,3), 'FaceColor', 'cyan', 'FaceAlpha', 0.8); Example 3: % Direct query of a 3D Delaunay triangulation created using % delaunayTriangulation. Compute the free boundary as in Example 2 Points = rand(50,3); dt = delaunayTriangulation(Points); [tri, Xb] = freeBoundary(dt); %Plot the surface mesh trisurf(tri, Xb(:,1), Xb(:,2), Xb(:,3), 'FaceColor', 'cyan','FaceAlpha', 0.8); triangulation methods: barycentricToCartesian - Converts the coordinates of a point from Barycentric to Cartesian cartesianToBarycentric - Converts the coordinates of a point from Cartesian to Barycentric circumcenter - Circumcenter of triangle or tetrahedron edgeAttachments - Triangles or tetrahedra attached to an edge edges - Triangulation edges faceNormal - Triangulation face normal featureEdges - Triangulation sharp edges freeBoundary - Triangulation facets referenced by only one triangle or tetrahedron incenter - Incenter of triangle or tetrahedron isConnected - Test if a pair of vertices is connected by an edge neighbors - Neighbors to a triangle or tetrahedron vertexAttachments - Triangles or tetrahedra attached to a vertex vertexNormal - Triangulation vertex normal size - Size of the triangulation ConnectivityList nearestNeighbor - Vertex closest to a specified point pointLocation - Triangle or tetrahedron containing a specified point triangulation properties: Points - The coordinates of the points in the triangulation ConnectivityList - The triangulation connectivity list See also delaunayTriangulation. Documentation for triangulation doc triangulation Other uses of triangulation polyshape/triangulation

类三角测量的方法:barycentricToCartesian edgeAttachments featureEdges与pointLocation vertexAttachments cartesianToBarycentric边缘freeBoundary nearestNeighbor大小vertexNormal外心faceNormal内心邻居三角

包含指定点TI = pointLocation pointLocation三角形或四面体(T, QP)返回的索引查询点QP三角形/四面体封闭。矩阵QP包含查询点的坐标。QP是mpt mpts-by-ndim矩阵,是查询的数量分和2 < = ndim < = 3。透明国际是一个列向量三角形或四面体id对应T.ConnectivityList三角连接矩阵的行数。三角形/四面体封闭点QP (k,:)是TI (k)。返回NaN的点不是位于三角形或四面体T TI = pointLocation (T QX、QY)和TI = pointLocation (T QX、QY,求出)允许查询点时在替代列向量指定格式在2 d和3 d工作。(钛、BC) = pointLocation (T,…)的回报,此外,公元前质心坐标。公元前公元前mpts-by-ndim矩阵,每一行(我:)代表的质心坐标QP(我:)对封闭TI(我)。示例1:%点位置在2 d T =三角([1 2 4;1 4 3; 2 4 5],[0 0; 2 0; 0 1; 1 1; 2 1]); % Find the triangle that contains the following query point QP = [1, 0.5]; triplot(T,'-b*'), hold on plot(QP(:,1),QP(:,2),'ro') % The query point QP is located in a triangle with index TI = 1 TI = pointLocation(T, QP) Example 2: % Point Location in 3D plus barycentric coordinate evaluation % for a Delaunay triangulation x = rand(10,1); y = rand(10,1); z = rand(10,1); DT = delaunayTriangulation(x,y,z); % Find the tetrahedra that contain the following query points QP = [0.25 0.25 0.25; 0.5 0.5 0.5] [TI, BC] = pointLocation(DT, QP) See also triangulation, triangulation.nearestNeighbor, delaunayTriangulation. Documentation for triangulation/pointLocation doc triangulation/pointLocation