释义 |
Point-Point Distance--3-DThe Line Element is
 | (1) |
so the Arc Length between the points and is
 | (2) |
and the quantity we are minimizing is
 | (3) |
Finding the derivatives gives
and
so the Euler-Lagrange Differential Equations become
These give
 | (10) |
 | (11) |
Taking the ratio,
 | (12) |
 | (13) |
 | (14) |
which gives
 | (15) |
 | (16) |
Therefore, and , so the solution is
 | (17) |
which is the parametric representation of a straight line with parameter . Verifying the Arc Length gives
 | (18) |
where
 | (19) |
 | (20) |
See also Point-Point Distance--1-D, Point-Point Distance--2-D,Point-Quadratic Distance |