# partial derivative notation question

• December 13th 2012, 09:05 PM
kingsolomonsgrave
partial derivative notation question
Attachment 26219

what does the notation at the bottom mean? the second derivative wrt z over the partial of y times the partial of x. Is that right? and what does that mean procedurally?
• December 13th 2012, 09:27 PM
MarkFL
Re: partial derivative notation question
It means to first take the partial derivative of z with respect to y, then take the partial derivative of this result with respect to x.

For a function like this which is continuous and the respective partials exist, the order of differentiation does not matter, i.e.:

$\frac{\delta^2 z}{\delta x\delta y}=\frac{\delta^2 z}{\delta y\delta x}$