let A be non empty closed_interval Subset of REAL; integral (((AffineMap (1,0)) (#) exp_R),A) = ((exp_R (#) (AffineMap (1,(- 1)))) . (upper_bound A)) - ((exp_R (#) (AffineMap (1,(- 1)))) . (lower_bound A))
A1:
for x being Real st x in REAL holds
(AffineMap (1,(- 1))) . x = x - 1
A2:
dom (exp_R (#) (AffineMap (1,(- 1)))) = [#] REAL
by FUNCT_2:def 1;
A3:
for x being Real st x in REAL holds
((AffineMap (1,0)) (#) exp_R) . x = x * (exp_R . x)
A4:
for x being Real st x in dom ((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) holds
((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) . x = ((AffineMap (1,0)) (#) exp_R) . x
proof
let x be
Real;
( x in dom ((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) implies ((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) . x = ((AffineMap (1,0)) (#) exp_R) . x )
assume
x in dom ((exp_R (#) (AffineMap (1,(- 1)))) `| REAL)
;
((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) . x = ((AffineMap (1,0)) (#) exp_R) . x
((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) . x =
x * (exp_R . x)
by A2, A1, FDIFF_4:55
.=
((AffineMap (1,0)) (#) exp_R) . x
by A3
;
hence
((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) . x = ((AffineMap (1,0)) (#) exp_R) . x
;
verum
end;
A5:
[#] REAL = dom ((AffineMap (1,0)) (#) exp_R)
by FUNCT_2:def 1;
( dom (AffineMap (1,0)) = [#] REAL & ( for x being Real st x in REAL holds
(AffineMap (1,0)) . x = (1 * x) + 0 ) )
by FCONT_1:def 4, FUNCT_2:def 1;
then
AffineMap (1,0) is_differentiable_on REAL
by FDIFF_1:23;
then
(AffineMap (1,0)) (#) exp_R is_differentiable_on REAL
by A5, FDIFF_1:21, TAYLOR_1:16;
then A6:
((AffineMap (1,0)) (#) exp_R) | REAL is continuous
by FDIFF_1:25;
then
((AffineMap (1,0)) (#) exp_R) | A is continuous
by FCONT_1:16;
then A7:
(AffineMap (1,0)) (#) exp_R is_integrable_on A
by A5, INTEGRA5:11;
exp_R (#) (AffineMap (1,(- 1))) is_differentiable_on REAL
by A2, A1, FDIFF_4:55;
then
dom ((exp_R (#) (AffineMap (1,(- 1)))) `| REAL) = dom ((AffineMap (1,0)) (#) exp_R)
by A5, FDIFF_1:def 7;
then A8:
(exp_R (#) (AffineMap (1,(- 1)))) `| REAL = (AffineMap (1,0)) (#) exp_R
by A4, PARTFUN1:5;
((AffineMap (1,0)) (#) exp_R) | A is bounded
by A5, A6, FCONT_1:16, INTEGRA5:10;
hence
integral (((AffineMap (1,0)) (#) exp_R),A) = ((exp_R (#) (AffineMap (1,(- 1)))) . (upper_bound A)) - ((exp_R (#) (AffineMap (1,(- 1)))) . (lower_bound A))
by A2, A1, A7, A8, FDIFF_4:55, INTEGRA5:13; verum