# When can one Change order of derivatives?

1. Jan 16, 2012

### Charanjit

Here is an example...

d/dz(dp/dx) = d/dx(dp/dz)

I dont remember learning this in my calculus or differential equations classes unless it was called something else.

2. Jan 16, 2012

### Simon Bridge

Those would be mixed partial derivatives.
Look it up.

The short answer is: almost always.

Last edited: Jan 16, 2012
3. Jan 16, 2012

### Charanjit

Hmm...ok never knew that. Thanks.