Thanks, your explanation is completely clear.

What does the expression "a(x),b(x)" mean?

@Markiyan Hirnyk 

Thanks, this works....

@tomleslie 

Thanks, it works. 

@Kitonum 

Indeed, it is shorter, but I need subs, because other substitutions, except functions, are used in expressions.

@vv 

Thanks, it works!

Please, consider FromMatlab operator enabling to convert some Matlab statements into Maple ones.

@Markiyan Hirnyk 

Please, take into account, that the functions U1(x), U(x) are continuous, and f(x) is integrable. So, the function under integral is integrable, and integral converges.

Thanks, Bulat.

At last, I've understood your.

Булат, поясни твой вопрос. Каждая Problem начинается с раздела Solution, т.е. задача уже решена! Тебе нужно проверить это решение или что-то еще? Я не знаю квантовой механики и, возможно, не улавливаю какой-то смысл.

I've downloaded the book and written the Problem 45. 

To be honest, I am far from Quantum mechanics, but can try to undestand the problem as a mathematical task. As I understood, Problem 45 is not a problem requred to be solved. Description of the problem has no unsolved questions. Maybe, you intend to verify implications entering in the description of the problem. Please, clarify your question.

@Preben Alsholm 

Thank you, but for some reasons it is essential to use output = Array option. 

Thank you for exlanation, I realized, that equation has no enough smoothness.

Булат, размести ссылку, откуда можно загрузить странички в нормальном разрешении.

На твоих снимках очень плохо видны детали.

И постарайся перейти на более высокую версию Maple.

Thank you. It works.

@Zihan 

Yes, see the source, please.

Exported LaTeX file has the separators \\ for separating the lines.

I only inserted the enviroment array and the formula gets ready!