let r be Real; ( 0 < r implies ex M, L being Real st
( 0 <= M & 0 <= L & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) ) ) )
assume A1:
r > 0
; ex M, L being Real st
( 0 <= M & 0 <= L & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) ) )
take M = exp_R . r; ex L being Real st
( 0 <= M & 0 <= L & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) ) )
take L = r; ( 0 <= M & 0 <= L & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) ) )
now let n be
Element of
NAT ;
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !)now A2:
for
a,
b being
Real st
0 <= a &
a <= b holds
for
n being
Element of
NAT holds
(
0 <= a |^ n &
a |^ n <= b |^ n )
let x,
s be
Real;
( x in ].(- r),r.[ & 0 < s & s < 1 implies abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) )assume that A8:
x in ].(- r),r.[
and A9:
0 < s
and A10:
s < 1
;
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !)
x in ].(0 - r),(0 + r).[
by A8;
then A11:
abs (x - 0) < r
by RCOMP_1:1;
abs x >= 0
by COMPLEX1:46;
then A12:
(abs x) |^ n <= L |^ n
by A11, A2;
A13:
n ! > 0
by NEWTON:17;
abs x >= 0
by COMPLEX1:46;
then
s * (abs x) < 1
* r
by A9, A10, A11, XREAL_1:97;
then
(abs s) * (abs x) < r
by A9, ABSVALUE:def 1;
then
abs ((s * x) - 0) < r
by COMPLEX1:65;
then A14:
s * x in ].(0 - r),(0 + r).[
by RCOMP_1:1;
then A15:
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) =
abs (((exp_R . (s * x)) * (x |^ n)) / (n !))
by Th7
.=
abs ((exp_R . (s * x)) * ((x |^ n) / (n !)))
by XCMPLX_1:74
.=
(abs (exp_R . (s * x))) * (abs ((x |^ n) / (n !)))
by COMPLEX1:65
;
exp_R . (s * x) >= 0
by SIN_COS:54;
then A16:
(
r in ([#] REAL) /\ (dom exp_R) &
abs (exp_R . (s * x)) = exp_R . (s * x) )
by ABSVALUE:def 1, TAYLOR_1:16;
for
x0 being
Real holds
0 <= diff (
exp_R,
x0)
by TAYLOR_1:16;
then A17:
exp_R | ([#] REAL) is
non-decreasing
by FDIFF_2:39, TAYLOR_1:16;
abs ((x |^ n) / (n !)) =
(abs (x |^ n)) / (abs (n !))
by COMPLEX1:67
.=
(abs (x |^ n)) / (n !)
by A13, ABSVALUE:def 1
.=
((abs x) |^ n) / (n !)
by Th1
;
then A18:
abs ((x |^ n) / (n !)) <= (L |^ n) / (n !)
by A13, A12, XREAL_1:72;
A19:
(
abs (exp_R . (s * x)) >= 0 &
abs ((x |^ n) / (n !)) >= 0 )
by COMPLEX1:46;
s * x in { p where p is Real : ( - r < p & p < r ) }
by A14, RCOMP_1:def 2;
then
ex
g being
Real st
(
g = s * x &
- r < g &
g < r )
;
then
abs (exp_R . (s * x)) <= M
by A17, A16, RFUNCT_2:24, TAYLOR_1:16;
then
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= M * ((L |^ n) / (n !))
by A19, A18, A15, XREAL_1:66;
hence
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !)
by XCMPLX_1:74;
verum end; hence
for
x,
s being
Real st
x in ].(- r),r.[ &
0 < s &
s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !)
;
verum end;
hence
( 0 <= M & 0 <= L & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
abs (((((diff (exp_R,].(- r),r.[)) . n) . (s * x)) * (x |^ n)) / (n !)) <= (M * (L |^ n)) / (n !) ) )
by A1, SIN_COS:54; verum