Origin for each line in src/integral.txt from check-in 5ce5316a33:

5ce5316a33 2021-03-01    1: y:=e^(-x)*sin (x);
5ce5316a33 2021-03-01    2: int (y, x, 0, infinity);
5ce5316a33 2021-03-01    3: int (e^(-x)*sin (x), x, 0, infinity);
5ce5316a33 2021-03-01    4: y;
5ce5316a33 2021-03-01    5: df (y, x);
5ce5316a33 2021-03-01    6: int (y, x);
5ce5316a33 2021-03-01    7: g:=ws;
5ce5316a33 2021-03-01    8: gup:=limit (g, x, infinity);
5ce5316a33 2021-03-01    9: glw:=sub (x=0, g);
5ce5316a33 2021-03-01   10: f:=gup-glw;
5ce5316a33 2021-03-01   11: end;