# Question:Very urgent!!I was try to use the command "expand" but it going error, (in property/ConvertProperty) invalid input: PropRange uses a 2nd argument, b, which is missing

## Question:Very urgent!!I was try to use the command "expand" but it going error, (in property/ConvertProperty) invalid input: PropRange uses a 2nd argument, b, which is missing

Maple 18

Just like the title described, I have encountered an error when I use the command "expand". Actually, I just follow the example, but it doesn't work. Please help me or tell me how can I solve it in other commands.

```
restart;
alias(epsilon = e, omega = w, omega = w0, t = t1, t = t2); e := proc (t1, t2) options operator, arrow; e end proc; w0 := proc (t1, t2) options operator, arrow; w0 end proc; a := proc (t1, t2) options operator, arrow; a end proc; f := proc (t1, t2) options operator, arrow; f end proc; mu := proc (t1, t2) options operator, arrow; mu end proc;
ode := (D@@2)(u)+2*mu*e*D(u)+w0^2*u+e*w0^2*u^3-e*f*cos(omega*t) = 0;
2
@@(D, 2)(u) + 2 mu epsilon D(u) + omega  u

2  3
+ epsilon omega  u  - epsilon f cos(omega t) = 0
e_oredr := 1;
ode := simplify(subs(D = sum('e^(i-1)*D[i]', 'i' = 1 .. e_oredr+1), ode), {e^(e_oredr+1) = 0});
/ 3         2
\u  omega  + 2 (epsilon D + D)(u) mu - cos(omega t) f

\                   2
+ 2 D[1, 2](u)/ epsilon + omega  u + D[1, 1](u) = 0
simplify(collect(%, e), {e^(e_oredr+1) = 0});

u := sum('v[i]*e^i', 'i' = 0 .. e_oredr);
epsilon v + v
ode := simplify(collect(ode, e), {e^2 = 0});
for i from 0 to e_oredr do eq[i] := coeff(lhs(ode), e, i) = 0 end do;
2
omega  v + D[1, 1](v) = 0
3         2           2
v  omega  + omega  v + 2 D(v) mu

- cos(omega t) f + 2 D[1, 2](v) + D[1, 1](v) = 0
remove(has, lhs(eq), cos); convert(%(t1, t2), diff);
eq := %-convert(f*cos(sigma*t2+t1*w0), 'exp');

v := A(t2)*cos(w0*t1+B(t2)); convert(%, 'exp'); v := unapply(%, t1, t2);
/1
(t1, t2) -> A(t2) |- exp(I (omega t1 + B(t2)))
\2

1                              \
+ - exp(-I (omega t1 + B(t2)))|
2                              /

expand(eq);
Error, (in property/ConvertProperty) invalid input: PropRange uses a 2nd argument, b, which is missing
collect(%, exp(I*w0*t1));
Error, (in collect) invalid 1st argument proc (t1, t2) options operator, arrow; A(t2)*((1/2)*exp(I*(w0*t1+B(t2)))+(1/2)*exp(-I*(w0*t1+B(t2)))) end proc
coeff(%, exp(I*w0*t1));
map(proc (x) options operator, arrow; x*exp(-I*B(t2)) end proc, %);
combine(%, 'exp');
subs(I*B(t2) = I*sigma*t2-I*C(t2), B(t2) = sigma*t2-C(t2), %);
conds := combine(%, 'exp');
0
``` ﻿