[Tugindia] derivative at a point

[Baburaj A. Puthenveettil]

Hi,
	Sorry, if this is too trivial for the list, but I couldnt find
anything easy for this
	
	I need to write dt 
                        ---| 
                        dz |
			   |y=0

I tried \frac{\partial t }{\partial z }\arrowvert_{y=0} and
....._{\arrowvert_{z=0}}

in both cases I do not get exactly what I would like to see. How do I make
the vertical line cover the full height(or the bottom 3/4th) of the
fraction, with y=0 as subscript slightly below the dz? is there some std 
math symbol that acheives this? 
regards 
Baburaj
					
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________________________________________________________________________________
Baburaj A.Puthenveettil, 
Office:                                       Current Residence:         
F.M.Lab, Dept of Mech Engg,                     U68, IISc           
IISc, Bangalore, 560012                  Ph: 91 080 3942624,3942591,3600265  
Ph: 91 080 3942302                                
Fax: 91 080 3600648 
email: apbabu at mecheng.iisc.ernet.in, apbraj at rediffmail.com
http://www.mecheng.iisc.ernet.in/~apbabu
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