# Clarification of PDE notation

1. Feb 10, 2010

### yungman

What is the meaning of $$\;\;\frac{\partial u}{\partial t}(x,0)$$

Is it equal to $$\;\;\frac{\partial u(x,t)}{\partial t}\;\;first\;then\;set\;t=0$$

or $$\;\;\;\frac{\partial u(x,0)}{\partial t}\;\;$$ Which is setting t=0 in u(x,t) first then differentiate?

2. Feb 10, 2010

### Lord Crc

Well, if you set t=0 and then differentiate with respect to t, you're not going to get much...

3. Feb 10, 2010

### yungman

Thanks

I just want to make double sure. Don't want to take anything for granted.

4. Feb 11, 2010

### Lord Crc

Good point :)