用逆风有限差分方法计算程函方程；
The upwind finite-difference method is used for traveltime calculations;
当前实用性较强的射线追踪方法，包括波前法，最短路径法，走时插值法，程函方程有限差分法等。
More practical ray tracing methods currently include the wavefront method, the shortest path method, the travel time epenthesis method, the eikonal equation finite difference method, etc.
本文提出一种将局部算法与扫描算法相结合的、用有限差分解程函方程求取地震波初至时间的方法。
A new technique is given here, which combines partial algorithm with scanning algorithm and obtains wave arrival times by solving eikonal equation with the use of finite difference method.
指出了以同一方程作为约束条件及欧拉方程的两个泛函之间的转换关系。
Conversion relations between two variational functionals that take respectively same equation as their constrain condition and Euler's equation are obtained.
指出了以同一方程作为约束条件及欧拉方程的两个泛函之间的转换关系。
Conversion relations between two variational functionals that take respectively same equation as their constrain condition and Euler's equation are obtained.
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