Question

我试图在postgresql中计算两个向量的交叉积。插图：输入：

edgex edgey edgez
6.80837996699847 39.4163159399759 0
0 0 12

使用查询

在postgresql中交叉产生这两行（向量）

Answer 1

为它创建一个函数。假设这些是3D点PostGIS几何：

CREATE OR REPLACE FUNCTION ST_CrossProduct(point_a geometry, point_b geometry)
  RETURNS geometry AS
$BODY$SELECT ST_SetSRID(ST_MakePoint(
  a2 * b3 - a3 * b2,
  a3 * b1 - a1 * b3,
  a1 * b2 - a2 * b1), ST_SRID($1))
FROM (SELECT
  ST_X($1) AS a1, ST_Y($1) AS a2, COALESCE(ST_Z($1), 0.0) AS a3,
  ST_X($2) AS b1, ST_Y($2) AS b2, COALESCE(ST_Z($2), 0.0) AS b3
) AS f$BODY$
LANGUAGE sql IMMUTABLE;

使用它：

SELECT ST_AsText(ST_CrossProduct(
     ST_MakePoint(6.80837996699847, 39.4163159399759, 0),
     ST_MakePoint(0, 0, 12)));

                   st_astext                    
------------------------------------------------
 POINT Z (472.995791279711 -81.7005596039816 0)
(1 row)

postgresql中两个向量（行）的交叉乘积

1 个答案: