The discussion focuses on finding the derivative ∂r/∂x_j, where r is defined as the modulus of a vector, specifically r = |x|. Participants clarify that differentiating the modulus of a vector involves expressing r in terms of its components, leading to the conclusion that r can be represented as a function of its components, r = f(x1, x2, x3, ...). This approach simplifies the differentiation process and makes it clear how to proceed with the calculation.
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phyzguy said:Try writing r out in components, i.e. r = f(x1,x2,x3,...) and I think it will be obvious what you need to do.