ϑʔϦΤڃల։ͱ
• 2 π पظؔΛ sin ͱ cos ʹղʢʹల։ʣ
• Իॲཧɺը૾ॲཧʹར༻
• ϑʔϦΤมɺϑʔϦΤڃల։ͷ֦ு
• पظؔͰͳͯ͘ల։Մೳ
f(x) =
a0
2
+
1
X
k=1
(ak cos kx + bk sin kx)
ak =
1
⇡
Z ⇡
⇡
f(x) cos kx dx
bk =
1
⇡
Z ⇡
⇡
f(x) sin kx dx
Slide 5
Slide 5 text
f
(
x
) =a0
2
Slide 6
Slide 6 text
f(x) =
a0
2
+ a1 cos 1x + b1 sin 1x
Slide 7
Slide 7 text
f(x) =
a0
2
+ a1 cos 1x + b1 sin 1x + a2 cos 2x + b2 sin 2x
Slide 8
Slide 8 text
f(x) =
a0
2
+ a1 cos 1x + b1 sin 1x + a2 cos 2x + b2 sin 2x
+ a3 cos 3x + b3 sin 3x
Slide 9
Slide 9 text
f(x) =
a0
2
+ a1 cos 1x + b1 sin 1x + a2 cos 2x + b2 sin 2x
+ a3 cos 3x + b3 sin 3x + a4 cos 4x + b4 sin 4x + a5 cos 5x + b5 sin 5x
Slide 10
Slide 10 text
f(x) =
a0
2
+ a1 cos 1x + b1 sin 1x + a2 cos 2x + b2 sin 2x
+ a3 cos 3x + b3 sin 3x + a4 cos 4x + b4 sin 4x + a5 cos 5x + b5 sin 5x
+ a6 cos 6x + b6 sin 6x + a7 cos 7x + b7 sin 7x + a7 cos 7x + b7 sin 7x
Slide 11
Slide 11 text
ͷٻΊํෳࡶ͗͢
• ͳͥ͜Μͳܗͳͷ͔ʁ
➡ ϕΫτϧ͔ΒͷྨਪͰཧղՄೳʂ
f(x) =
a0
2
+
1
X
k=1
(ak cos kx + bk sin kx)
ak =
1
⇡
Z ⇡
⇡
f(x) cos kx dx
bk =
1
⇡
Z ⇡
⇡
f(x) sin kx dx
ؔΛࡾ֯ؔͰղ
• ͜Ε͕ϑʔϦΤڃల։
• ੵΛ͍͍ײ͡ʹܾΊ͍ͨ
➡ ࡾ͕֯ؔਖ਼نަجఈͱͳΔΑ͏ʹੵΛఆٛ
f =
a0
2
+ < f, cos 1x > cos 1x+ < f, cos 2x > cos 2x + . . .
+ < f, sin 1x > sin 1x+ < f, sin 2x > sin 2x + . . .
Slide 33
Slide 33 text
ϑʔϦΤڃల։ͷͨΊͷੵ
< f, g >
=
1
⇡
Z ⇡
⇡
fg dx
Slide 34
Slide 34 text
ϑʔϦΤڃల։ͷͨΊͷੵ
• ੵΛ͜ͷΑ͏ʹఆٛ͢ΕɺҎԼ͕ຬͨ͞ΕΔɿ
< f, g >
=
1
⇡
Z ⇡
⇡
fg dx
< cos ix, cos jx > = ij
< sin ix, sin jx > = ij
< cos ix, sin jx > = 0
Slide 35
Slide 35 text
f(x) =
a0
2
+
1
X
k=1
(ak cos kx + bk sin kx)
ak =
1
⇡
Z ⇡
⇡
f(x) cos kx dx
bk =
1
⇡
Z ⇡
⇡
f(x) sin kx dx
Slide 36
Slide 36 text
f(x) =
a0
2
+
1
X
k=1
(ak cos kx + bk sin kx)
ak =
1
⇡
Z ⇡
⇡
f(x) cos kx dx
bk =
1
⇡
Z ⇡
⇡
f(x) sin kx dx
=< f, cos kx >
=< f, sin kx >
=< f, cos kx >
=< f, sin kx >