I am having problems with the code I am trying to write in Maple 2020. I have attached the code in this question. 

I hope someone can help me out.

Error, invalid input: rhs received 0, which is not valid for its 1st argument, expr

Thanks very much
 

Download EXAMPLE.mw

I'm currently working my thesis and can someone help me to write a code to solve this IVP

u_t + 2×u²×u_x−(u_x)²−½×u_{xx}×u=0

with initial condition

u(x,0)=-tanh(x)