restart;q1:=sin(omega*(T0-T)+Phi);map(expand,q1);q2:=sin(omega*(T0-T)+phi);Notice the Maple has changed rearranged to have a minus before the sin.map(expand,q2);map applies expand to each operand. For q1, the only operand is the argument to sin, but Maple considers q2 as a product of two operands, the -1 and the sin, so it expands bothwhattype(q1);op(q1);whattype(q2);op(q2);To get what you want requires you to operate the expand on the (first) operand of the second operand, which can be done as followsapplyop(expand,[2,1],q2);But this is a rather complicated solution, which requires attention in individual cases. Of course you could just stick with Phi. In general, getting Maple to rearrange things into the exact form you want is difficult. Depending on your ultimate objective, it may not be worth it. But perhaps others have a simpler solution.