valid approximation的意思|示意

The method is valid when Fresnel approximation isn't satisfied, can be further applied for reconstruction of digital holograms with variable...

即使在菲涅耳近似不满足的情况下，该方法依然有效，可进一步用于数字全息的多平面和多角度的重建。

For any approximation to be valid it must provide a result that is in some sense close to the solution of the original problem.

任何有效的近似式必须在某种意义上提供一个接近于原问题解的结果。

The former correct for the varying time-delays by using an approximation of the binary orbit which is valid only if the observation time is much less than the orbital period of the binary system.

前一种通过近似的双星轨道对时间延迟进行修正，只在观测时间远小于双星系统的轨道周期时才有效。