Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

given that $z=f(x,y)$ and $x =r\cos(\theta)$ and y = $r\sin(\theta)$

$d^2(z)/d(r)^2$ and $d^2(z)/d(r)$

are both second derivatives of the function $z$? I am getting a little confused with all the notations.

share|improve this question

1 Answer 1

up vote 2 down vote accepted

The notation for the first means $$ \frac{\partial^2 z}{\partial r^2} = \frac{\partial}{\partial r} \left( \frac{\partial z}{\partial r} \right),$$ so you take the partial derivative with respect to $r$ of the partial derivative of $z$ with respect to $r$, hence the "second derivative" of $z$ with respect to $r$.

The notation for the second quantity does not make sense, at least not according to anything I'm familiar with.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.