let A be closed-interval Subset of REAL; for f being PartFunc of REAL,REAL
for Z being open Subset of REAL st A c= Z & ( for x being Real st x in Z holds
x > 0 ) & Z = dom f & f = (sin * ln) (#) ((id Z) ^) holds
integral (f,A) = ((- (cos * ln)) . (upper_bound A)) - ((- (cos * ln)) . (lower_bound A))
let f be PartFunc of REAL,REAL; for Z being open Subset of REAL st A c= Z & ( for x being Real st x in Z holds
x > 0 ) & Z = dom f & f = (sin * ln) (#) ((id Z) ^) holds
integral (f,A) = ((- (cos * ln)) . (upper_bound A)) - ((- (cos * ln)) . (lower_bound A))
let Z be open Subset of REAL; ( A c= Z & ( for x being Real st x in Z holds
x > 0 ) & Z = dom f & f = (sin * ln) (#) ((id Z) ^) implies integral (f,A) = ((- (cos * ln)) . (upper_bound A)) - ((- (cos * ln)) . (lower_bound A)) )
assume A1:
( A c= Z & ( for x being Real st x in Z holds
x > 0 ) & Z = dom f & f = (sin * ln) (#) ((id Z) ^) )
; integral (f,A) = ((- (cos * ln)) . (upper_bound A)) - ((- (cos * ln)) . (lower_bound A))
then AA:
Z = dom ((sin * ln) / (id Z))
by RFUNCT_1:47;
Z = (dom (sin * ln)) /\ (dom ((id Z) ^))
by VALUED_1:def 4, A1;
then A4:
Z c= dom (sin * ln)
by XBOOLE_1:18;
for y being set st y in Z holds
y in dom (cos * ln)
then B6:
Z c= dom (cos * ln)
by TARSKI:def 3;
A6:
sin * ln is_differentiable_on Z
by FDIFF_7:32, A4, A1;
not 0 in Z
by A1;
then
(id Z) ^ is_differentiable_on Z
by FDIFF_5:4;
then
f | Z is continuous
by FDIFF_1:33, A1, A6, FDIFF_1:29;
then
f | A is continuous
by A1, FCONT_1:17;
then A11:
( f is_integrable_on A & f | A is bounded )
by A1, INTEGRA5:10, INTEGRA5:11;
A12:
cos * ln is_differentiable_on Z
by B6, A1, FDIFF_7:33;
A13:
Z c= dom (- (cos * ln))
by B6, VALUED_1:8;
then A14:
(- 1) (#) (cos * ln) is_differentiable_on Z
by A12, FDIFF_1:28, X;
A15:
for x being Real st x in Z holds
((- (cos * ln)) `| Z) . x = (sin . (ln . x)) / x
proof
let x be
Real;
( x in Z implies ((- (cos * ln)) `| Z) . x = (sin . (ln . x)) / x )
assume A16:
x in Z
;
((- (cos * ln)) `| Z) . x = (sin . (ln . x)) / x
then
x > 0
by A1;
then A18:
x in right_open_halfline 0
by Lm1;
A19:
ln is_differentiable_in x
by A16, A1, TAYLOR_1:18;
A20:
cos is_differentiable_in ln . x
by SIN_COS:68;
A21:
cos * ln is_differentiable_in x
by A12, A16, FDIFF_1:16;
((- (cos * ln)) `| Z) . x =
diff (
(- (cos * ln)),
x)
by A14, A16, FDIFF_1:def 8
.=
(- 1) * (diff ((cos * ln),x))
by A21, FDIFF_1:23, X
.=
(- 1) * ((diff (cos,(ln . x))) * (diff (ln,x)))
by A19, A20, FDIFF_2:13
.=
(- 1) * ((- (sin . (ln . x))) * (diff (ln,x)))
by SIN_COS:68
.=
(- 1) * ((- (sin . (ln . x))) * (1 / x))
by A18, TAYLOR_1:18
.=
(sin . (ln . x)) / x
;
hence
((- (cos * ln)) `| Z) . x = (sin . (ln . x)) / x
;
verum
end;
B7:
for x being Real st x in Z holds
f . x = (sin . (ln . x)) / x
A22:
for x being Real st x in dom ((- (cos * ln)) `| Z) holds
((- (cos * ln)) `| Z) . x = f . x
dom ((- (cos * ln)) `| Z) = dom f
by A1, A14, FDIFF_1:def 8;
then
(- (cos * ln)) `| Z = f
by A22, PARTFUN1:34;
hence
integral (f,A) = ((- (cos * ln)) . (upper_bound A)) - ((- (cos * ln)) . (lower_bound A))
by A1, A11, A12, A13, FDIFF_1:28, X, INTEGRA5:13; verum