i here i have a lot term in my function which this is the smallest function i have  and i need write a procedure for calculating them but my procedure not work 

how fix that 

nt.mw

i try to find the parameter in this equation but some issues show up which i am not sure i can fix that or not? there is any way for finding thus parameters?

test-F-p.mw

i did my try to sketch the best shape of graph by existing code but the 3D shape in matlab is not what i am looking and is  not intresting for this kind of plot so i want use and design a better shape of 3D plot for thus contour  i need help for that 

plot-help.mw

i did simplify and each time work but this time is give me another thing can anyone find what is problem?

pdetest2.mw

in here i did exactly the same but i am not sure the author did something mistake or i did becuase one term in the pde is change and how exactly do that replacement in eq62?

S.mw