voltage calculation from electric field

hi to all,

i have simulated a structure using fdtd method. i got ex as a electric field in the x direction. ex is a 50×50 matrix. i need to find voltage from elctric field in a particular point in matlab.

i have used int command in matlab, but it is not working . plz someone help me

just sum all field along a line then you can get voltage
remember V =int(E)dl=E(i,j)*dx+E(i+1,j)*dx)....
hope you can understand my poor english,

hai snow land ,
thanks for ur help.
then wat i hav to do to get indutance and capacitance of the transmission line from the fdtd field values.
how i can perform differentiation in matlab.