let r be Real; :: thesis: ( r > 0 implies ex r1, r2 being Real st
( r1 >= 0 & r2 >= 0 & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) ) ) )
assume A1:
r > 0
; :: thesis: ex r1, r2 being Real st
( r1 >= 0 & r2 >= 0 & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) ) )
take r1 = 1; :: thesis: ex r2 being Real st
( r1 >= 0 & r2 >= 0 & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) ) )
take r2 = r; :: thesis: ( r1 >= 0 & r2 >= 0 & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) ) )
now let n be
Element of
NAT ;
:: thesis: for x, s being Real st x in ].(- r),r.[ & s > 0 & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) )let x,
s be
Real;
:: thesis: ( x in ].(- r),r.[ & s > 0 & s < 1 implies ( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) )assume A2:
(
x in ].(- r),r.[ &
s > 0 &
s < 1 )
;
:: thesis: ( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) )
x in ].(0 - r),(0 + r).[
by A2;
then A3:
abs (x - 0 ) < r
by RCOMP_1:8;
abs x >= 0
by COMPLEX1:132;
then
s * (abs x) < 1
* r
by A2, A3, XREAL_1:99;
then
(abs s) * (abs x) < r
by A2, ABSVALUE:def 1;
then
abs ((s * x) - 0 ) < r
by COMPLEX1:151;
then A4:
s * x in ].(0 - r),(0 + r).[
by RCOMP_1:8;
A5:
n ! > 0
by NEWTON:23;
A6:
abs ((x |^ n) / (n ! )) =
(abs (x |^ n)) / (abs (n ! ))
by COMPLEX1:153
.=
(abs (x |^ n)) / (n ! )
by A5, ABSVALUE:def 1
.=
((abs x) |^ n) / (n ! )
by Th1
;
A7:
abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) =
abs ((((diff sin ,].(- r),r.[) . n) . (s * x)) * ((x |^ n) / (n ! )))
by XCMPLX_1:75
.=
(abs (((diff sin ,].(- r),r.[) . n) . (s * x))) * (abs ((x |^ n) / (n ! )))
by COMPLEX1:151
.=
((abs (((diff sin ,].(- r),r.[) . n) . (s * x))) * ((abs x) |^ n)) / (n ! )
by A6, XCMPLX_1:75
;
A8:
abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) =
abs ((((diff cos ,].(- r),r.[) . n) . (s * x)) * ((x |^ n) / (n ! )))
by XCMPLX_1:75
.=
(abs (((diff cos ,].(- r),r.[) . n) . (s * x))) * (abs ((x |^ n) / (n ! )))
by COMPLEX1:151
.=
((abs (((diff cos ,].(- r),r.[) . n) . (s * x))) * ((abs x) |^ n)) / (n ! )
by A6, XCMPLX_1:75
;
A9:
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) >= 0
by COMPLEX1:132;
A10:
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) >= 0
by COMPLEX1:132;
A11:
((abs x) |^ n) / (n ! ) >= 0
by A6, COMPLEX1:132;
A12:
for
k being
Element of
NAT holds
abs ((- 1) |^ k) = 1
A15:
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) <= r1
proof
per cases
( n is even or not n is even )
;
suppose
n is
even
;
:: thesis: abs (((diff sin ,].(- r),r.[) . n) . (s * x)) <= r1then consider k being
Element of
NAT such that A16:
n = 2
* k
by ABIAN:def 2;
A17:
dom (((- 1) |^ k) (#) (sin | ].(- r),r.[)) =
dom (sin | ].(- r),r.[)
by VALUED_1:def 5
.=
].(- r),r.[
by Th17
;
A18:
s * x in dom (sin | ].(- r),r.[)
by A4, Th17;
A19:
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) =
abs ((((- 1) |^ k) (#) (sin | ].(- r),r.[)) . (s * x))
by A16, Th19
.=
abs (((- 1) |^ k) * ((sin | ].(- r),r.[) . (s * x)))
by A4, A17, VALUED_1:def 5
.=
(abs ((- 1) |^ k)) * (abs ((sin | ].(- r),r.[) . (s * x)))
by COMPLEX1:151
.=
1
* (abs ((sin | ].(- r),r.[) . (s * x)))
by A12
.=
abs (sin . (s * x))
by A18, FUNCT_1:70
;
abs (sin (s * x)) <= 1
by SIN_COS:30;
hence
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) <= r1
by A19, SIN_COS:def 21;
:: thesis: verum end; suppose
not
n is
even
;
:: thesis: abs (((diff sin ,].(- r),r.[) . n) . (s * x)) <= r1then consider k being
Element of
NAT such that A20:
n = (2 * k) + 1
by ABIAN:9;
A21:
dom (((- 1) |^ k) (#) (cos | ].(- r),r.[)) =
dom (cos | ].(- r),r.[)
by VALUED_1:def 5
.=
].(- r),r.[
by Th17
;
A22:
s * x in dom (cos | ].(- r),r.[)
by A4, Th17;
A23:
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) =
abs ((((- 1) |^ k) (#) (cos | ].(- r),r.[)) . (s * x))
by A20, Th19
.=
abs (((- 1) |^ k) * ((cos | ].(- r),r.[) . (s * x)))
by A4, A21, VALUED_1:def 5
.=
(abs ((- 1) |^ k)) * (abs ((cos | ].(- r),r.[) . (s * x)))
by COMPLEX1:151
.=
1
* (abs ((cos | ].(- r),r.[) . (s * x)))
by A12
.=
abs (cos . (s * x))
by A22, FUNCT_1:70
;
abs (cos (s * x)) <= 1
by SIN_COS:30;
hence
abs (((diff sin ,].(- r),r.[) . n) . (s * x)) <= r1
by A23, SIN_COS:def 23;
:: thesis: verum end; end;
end; A24:
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) <= r1
proof
per cases
( n is even or not n is even )
;
suppose
n is
even
;
:: thesis: abs (((diff cos ,].(- r),r.[) . n) . (s * x)) <= r1then consider k being
Element of
NAT such that A25:
n = 2
* k
by ABIAN:def 2;
A26:
dom (((- 1) |^ k) (#) (cos | ].(- r),r.[)) =
dom (cos | ].(- r),r.[)
by VALUED_1:def 5
.=
].(- r),r.[
by Th17
;
A27:
s * x in dom (cos | ].(- r),r.[)
by A4, Th17;
A28:
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) =
abs ((((- 1) |^ k) (#) (cos | ].(- r),r.[)) . (s * x))
by A25, Th19
.=
abs (((- 1) |^ k) * ((cos | ].(- r),r.[) . (s * x)))
by A4, A26, VALUED_1:def 5
.=
(abs ((- 1) |^ k)) * (abs ((cos | ].(- r),r.[) . (s * x)))
by COMPLEX1:151
.=
1
* (abs ((cos | ].(- r),r.[) . (s * x)))
by A12
.=
abs (cos . (s * x))
by A27, FUNCT_1:70
;
abs (cos (s * x)) <= 1
by SIN_COS:30;
hence
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) <= r1
by A28, SIN_COS:def 23;
:: thesis: verum end; suppose
not
n is
even
;
:: thesis: abs (((diff cos ,].(- r),r.[) . n) . (s * x)) <= r1then consider k being
Element of
NAT such that A29:
n = (2 * k) + 1
by ABIAN:9;
A30:
dom (((- 1) |^ (k + 1)) (#) (sin | ].(- r),r.[)) =
dom (sin | ].(- r),r.[)
by VALUED_1:def 5
.=
].(- r),r.[
by Th17
;
A31:
s * x in dom (sin | ].(- r),r.[)
by A4, Th17;
A32:
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) =
abs ((((- 1) |^ (k + 1)) (#) (sin | ].(- r),r.[)) . (s * x))
by A29, Th19
.=
abs (((- 1) |^ (k + 1)) * ((sin | ].(- r),r.[) . (s * x)))
by A4, A30, VALUED_1:def 5
.=
(abs ((- 1) |^ (k + 1))) * (abs ((sin | ].(- r),r.[) . (s * x)))
by COMPLEX1:151
.=
1
* (abs ((sin | ].(- r),r.[) . (s * x)))
by A12
.=
abs (sin . (s * x))
by A31, FUNCT_1:70
;
abs (sin (s * x)) <= 1
by SIN_COS:30;
hence
abs (((diff cos ,].(- r),r.[) . n) . (s * x)) <= r1
by A32, SIN_COS:def 21;
:: thesis: verum end; end;
end;
((abs x) |^ n) / (n ! ) <= (r2 |^ n) / (n ! )
then
(
(abs (((diff sin ,].(- r),r.[) . n) . (s * x))) * (((abs x) |^ n) / (n ! )) <= r1 * ((r2 |^ n) / (n ! )) &
(abs (((diff cos ,].(- r),r.[) . n) . (s * x))) * (((abs x) |^ n) / (n ! )) <= r1 * ((r2 |^ n) / (n ! )) )
by A9, A10, A11, A15, A24, XREAL_1:68;
hence
(
abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) &
abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) )
by A7, A8, XCMPLX_1:75;
:: thesis: verum end;
hence
( r1 >= 0 & r2 >= 0 & ( for n being Element of NAT
for x, s being Real st x in ].(- r),r.[ & 0 < s & s < 1 holds
( abs (((((diff sin ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) & abs (((((diff cos ,].(- r),r.[) . n) . (s * x)) * (x |^ n)) / (n ! )) <= (r1 * (r2 |^ n)) / (n ! ) ) ) )
by A1; :: thesis: verum