> int( sin(x), x );
> smittel=1/T*(int (U, s=(-a*T/2)..(a*T/2)));
> cn=1/T*(int (U*exp(-I*n*w*t), t=(-a*T/2)..(a*T/2)));
> an=1/T*(int (U*cos(n*w*t), t=(-a*T/2)..(a*T/2)));
> bn=1/T*(int (U*sin(n*w*t), t=(-a*T/2)..(a*T/2)));
> convert(sin(p),exp);
>