I am not able to understand the top 2 lines on page 536 that are mentioned regarding the weight function mentioned in chapter 27 of ashcroft and mermin solid state physics book.(adsbygoogle = window.adsbygoogle || []).push({});

I don't get the statement where the authors state Igrad(f)I/f should not be appreciably greater than the minimum value, of order 1/ro ? Why inverse of length is used ?

I know grad(f) gives me the direction of maximum change in f but why has the author used Igrad(f)I/f for a slowly varying function ?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# A question on weight function from Ashcroft and Mermin book

**Physics Forums | Science Articles, Homework Help, Discussion**