let z be Complex; :: thesis: for CNS being ComplexNormSpace
for S being sequence of CNS st S is convergent holds
z * S is convergent
let CNS be ComplexNormSpace; :: thesis: for S being sequence of CNS st S is convergent holds
z * S is convergent
let S be sequence of CNS; :: thesis: ( S is convergent implies z * S is convergent )
assume S is convergent ; :: thesis: z * S is convergent
then consider g being Point of CNS such that
A1: for r being Real st 0 < r holds
ex m being Nat st
for n being Nat st m <= n holds
||.((S . n) - g).|| < r ;
take h = z * g; :: according to CLVECT_1:def 15 :: thesis: for r being Real st 0 < r holds
ex m being Nat st
for n being Nat st m <= n holds
||.(((z * S) . n) - h).|| < r
A2: now :: thesis: ( z <> 0c implies for r being Real st 0 < r holds
ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r )
assume A3: z <> 0c ; :: thesis: for r being Real st 0 < r holds
ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
then A4: 0 < |.z.| by COMPLEX1:47;
let r be Real; :: thesis: ( 0 < r implies ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r )
assume 0 < r ; :: thesis: ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
then consider m1 being Nat such that
A5: for n being Nat st m1 <= n holds
||.((S . n) - g).|| < r / |.z.| by A1, A4;
take k = m1; :: thesis: for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
let n be Nat; :: thesis: ( k <= n implies ||.(((z * S) . n) - h).|| < r )
assume k <= n ; :: thesis: ||.(((z * S) . n) - h).|| < r
then A6: ||.((S . n) - g).|| < r / |.z.| by A5;
A7: 0 <> |.z.| by A3, COMPLEX1:47;
A8: |.z.| * (r / |.z.|) = |.z.| * ((|.z.| ") * r) by XCMPLX_0:def 9
.= (|.z.| * (|.z.| ")) * r
.= 1 * r by A7, XCMPLX_0:def 7
.= r ;
||.((z * (S . n)) - (z * g)).|| = ||.(z * ((S . n) - g)).|| by Th9
.= |.z.| * ||.((S . n) - g).|| by Def13 ;
then ||.((z * (S . n)) - h).|| < r by A4, A6, A8, XREAL_1:68;
hence ||.(((z * S) . n) - h).|| < r by Def14; :: thesis: verum
end;
now :: thesis: ( z = 0 implies for r being Real st 0 < r holds
ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r )
assume A9: z = 0 ; :: thesis: for r being Real st 0 < r holds
ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
let r be Real; :: thesis: ( 0 < r implies ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r )
assume 0 < r ; :: thesis: ex k being Nat st
for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
then consider m1 being Nat such that
A10: for n being Nat st m1 <= n holds
||.((S . n) - g).|| < r by A1;
take k = m1; :: thesis: for n being Nat st k <= n holds
||.(((z * S) . n) - h).|| < r
let n be Nat; :: thesis: ( k <= n implies ||.(((z * S) . n) - h).|| < r )
assume k <= n ; :: thesis: ||.(((z * S) . n) - h).|| < r
then A11: ||.((S . n) - g).|| < r by A10;
||.((z * (S . n)) - (z * g)).|| = ||.((0c * (S . n)) - H1(CNS)).|| by A9, Th1
.= ||.(H1(CNS) - H1(CNS)).|| by Th1
.= ||.H1(CNS).|| by RLVECT_1:13
.= 0 ;
then ||.((z * (S . n)) - h).|| < r by A11, Th105;
hence ||.(((z * S) . n) - h).|| < r by Def14; :: thesis: verum
end;
hence for r being Real st 0 < r holds
ex m being Nat st
for n being Nat st m <= n holds
||.(((z * S) . n) - h).|| < r by A2; :: thesis: verum