let r, e be Real; ( 0 < r & 0 < e implies ex n being Nat st
for m being Nat st n <= m holds
for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e )
assume that
A1:
r > 0
and
A2:
e > 0
; ex n being Nat st
for m being Nat st n <= m holds
for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
consider n being Nat such that
A3:
for m being Nat st n <= m holds
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
|.(((((diff (exp_R,].(- r),r.[)) . m) . (s * x)) * (x |^ m)) / (m !)).| < e
by A1, A2, Th13;
take
n
; for m being Nat st n <= m holds
for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
let m be Nat; ( n <= m implies for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e )
assume A4:
n <= m
; for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
now for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
m <= m + 1
by NAT_1:11;
then A5:
n <= m + 1
by A4, XXREAL_0:2;
let x be
Real;
( x in ].(- r),r.[ implies |.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e )assume A6:
x in ].(- r),r.[
;
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
ex
s being
Real st
(
0 < s &
s < 1 &
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| = |.(((((diff (exp_R,].(- r),r.[)) . (m + 1)) . (s * x)) * (x |^ (m + 1))) / ((m + 1) !)).| )
by A1, A6, Th4, Th10, SIN_COS:47;
hence
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
by A3, A6, A5;
verum end;
hence
for x being Real st x in ].(- r),r.[ holds
|.((exp_R . x) - ((Partial_Sums (Maclaurin (exp_R,].(- r),r.[,x))) . m)).| < e
; verum