First write the expression in MATLAB syntax. MATLAB syntax does not have any implicit multiplication, and invocation of functions is always of the form FunctionName(parameter) . Exponentiation is the ^ operator .Also, e raised to a power is written using the function name exp
Once you have the expression in MATLAB syntax, create an anonymous function with two parameters, and pass that to fsurf().
Anonymous functions with two parameters look like @(x,y) FORMULA