reserve c for Complex;
reserve r for Real;
reserve m,n for Nat;
reserve f for complex-valued Function;

theorem Th10:
  for f being differentiable Function of REAL,REAL holds f`|.r = diff(f,r)
  proof
    let f be differentiable Function of REAL,REAL;
    dom f = REAL by FUNCT_2:def 1;
    then
A1: f is_differentiable_on REAL by FDIFF_1:def 8;
    r in REAL by XREAL_0:def 1;
    hence thesis by A1,FDIFF_1:def 7;
  end;
