thanks, that clears things up - i didn't realize that boundary conditions can only be used in a numerical solution. as for the derivative notation, is D[2](T)(y,0) the first derivative or the second derivative? would D[1](T) be the original function?

thanks, that clears things up - i didn't realize that boundary conditions can only be used in a numerical solution. as for the derivative notation, is D[2](T)(y,0) the first derivative or the second derivative? would D[1](T) be the original function?