ֶੜ࣮ݧʹ͓͚ΔϑʔϦΤղੳ
Some studies on Fourier analysis in students experimentେ࡚ਖ਼༤
Masao Osakiۄେֶֶ෦ιϑτΣΞαΠΤϯεֶՊ, 194–8610 ౦ژொాࢢۄֶԂ 6–1–1 College of Engineering, Tamagawa University,
6–1–1 Tamagawa-gakuen, Machida-shi, Tokyo 194–8610
Abstract
Here we give some troubles in teaching and their solutions occured during the Software Science Experiment course, which is opened for the 4th semester in the Department of Software Science. One of the subjects of this experiment course is Fourier analysis using MyPC. Some students are not familiar with calculating the integration of sinusoidal function, and also some need support for drawing graphs with MS Excel. Typical mistakes and their settlements are given.
Keywords: Students expreriment, Fourier analysis, troubles and their solutions.
1 ͡Ίʹ ຊֶֶ෦ιϑτΣΞαΠΤϯεֶՊͰ ʮιϑτΣΞαΠΤϯε࣮ݧIʢҎԼɼ࣮ݧIʣʯ ͱʮιϑτΣΞαΠΤϯε࣮ݧIIʢҎԼɼ࣮ݧ IIʣʯΛඞमՊͱ࣮ͯ͠ࢪ͖ͯͨ͠ɽͦΕͧΕ̐ ηϝελʔɼ̑ηϝελʔͰ։ߨ͞Εɼ࣮ݧʹΑ ΔݱѲͱɼͦΕΛϨϙʔτʹදٕ͢ज़ͷमಘ Λࢦ͍ͯͨ͠ɽ֤࣮ݧ̏ςʔϚͰߏ͞Εɼ ࣮ݧ̞ͰʮύιίϯʹΑΔ৴߸ղੳʯͱͯ͠ ϑʔϦΤղੳͷॳาΛमಘ͢ΔͷΛஶऀ୲ ͨ͠ɽ ຊߘͰɼͦͷ࣮ݧʹ͓͍ͯमಘΛࢦ߲ͨ͠ ɼͦͷख๏ɼͦ͜Ͱੜͨ͡ͱͦͷղܾํ๏ ʹ͍ͭͯड़Δɽͦ͜ʹݟΒΕΔز͔ͭͷ͕ ࣮ݧʹݶΒͣɼϑʔϦΤղੳʹؔ࿈͢Δߨٛʹ͓ ཱ͍͍ͯͯͰ͋Δɽ 2 ֶతجૅ ϑʔϦΤղੳͷୈҰาपظ৴߸ͷϑʔϦΤڃ ల։Ͱ͋ΔɽͦͷͨΊʹʮपظ৴߸ͷఆٛʯ ͱͦͷදྫͱͯ͠ͷʮਖ਼ݭ৴߸ͷੑ࣭ʯ͕ඞ ཁෆՄܽͰ͋ΔɽͦͷͨΊɼҎԼͷΑ͏ʹهͨ͠ɽ पظ৴߸ ৴߸f(t)͕पظT [sec.]Λ࣋ͭ߹ɼҙͷ࣌ ࠁtʹରͯ͠ҎԼͷ͕ؔΓཱͭɽ f(t) = f(t + T ). (1) વɼmΛͱͯ࣍͠ͷؔΓཱͭɽ f(t) = f(t + mT ). (2) ͜͜Ͱ࠷͍पظT ΛجຊपظͱݺͿɽ ਖ਼ݭ৴߸ Ұൠʹਖ਼ݭ৴߸ৼ෯AɼपfɼॳظҐ ૬θΛ༻͍ͯ࣍ࣜͰද͞ΕΔɽ f(t) = A sin[2πft + θ]. (3) ͜͜Ͱ໌Β͔ʹपظT = 1/f͕Γཱͭɽ ͞ΒʹϑʔϦΤڃల։ʮࡾ֯ؔͷަੑʯ Λࠜڌͱ͠ɼपظ৴߸ͷ࣌ؒܗΛجຊपͱ ͦͷߴௐ͔ΒͳΔपεϖΫτϧʹղ ͢ΔɽͦͷͨΊʮϕΫτϧͷੵ͕θϩʹͳΔͱ
ަ͢Δʯͱ͍͏֓೦ɼ۩ମతͳʮࡾ֯ؔͷ ੵʯͷٕज़͕ඞཁʹͳΔɽֶ͔͠͠ʮͦ ͏ݴ͏ͷͩʯͱ͍֮͑ͯͯɼղੳֶʢಛʹࡾ ֯ؔͷੵʣ͍֮͑ͯͳ͍͔ɼͦͦशͬ ͨ͜ͱ͕ແֶ͍ੜ೦ͳ͕ΒຊֶՊʹଘࡏ͢ ΔɽͦͷͨΊ࣮ݧIͰෆఆੵͷެ͕ࣜར༻Ͱ ͖ΔΑ͏ʹͳΔ͜ͱΛతͱͨ͠ɽ ۩ମతͳ༰ͱͯ͠sin 2πf tͱsin 2π(2f )t ͷҰपظʹΘͨΔੵΛݟͤɼͦͷաఔͷཧղ Λଅ͢͜ͱͰަੑͷྫͱͨ͠ɽͦΕʹଓ͍ͯ ֶੜ͕ࣗcos 2πf tͱcos 2π(2f )tɼsin 2πf tͱ
cos 2πf tͷަੑΛ֬ೝ͢Δ͜ͱΛԋशIͱͯ͠ ՝ͨ͠ɽ ަੑ ਖ਼ݭ৴߸ҟͳΔपΛؚ·ͳ͍ɽಉ͡ पظT [sec.]ͷਖ਼ݭ৴߸ͱͯ͠sin[2πf t]ʢf = 1/Tʣͱsin[2π(2f )t]ʢجຊपظT/2ʣΛߟ͑ Δɽ͜ͷͱ͖྆ऀͷੵΛҰपظʹΘͨΓੵ͢ Δͱ࣍ࣜΛಘΔɽ T/2 −T/2sin[2πf t]× sin[2π(2f)t]dt = T/2 −T/2 1 2(cos[(2πf t)− {2π(2f)t}] − cos[(2πft) + {2π(2f)t}]) dt = 1 2 T/2 −T/2(cos[−2πft] − cos[3 · 2πft]) dt = 1 2 −1 2πf sin[−2πft] − 1 6πf sin[6πf t] T 2 −T 2 = −1 4πf sin −2πfT 2 − sin −2πf−T 2 − 1 12πf sin 6πfT 2 − sin 6πf−T 2 ɹ = 0. (4) ͨͩ͠ f · T2 = T1 · T2 = 12, sin[±π] = sin[±3π] = 0Λ༻͍ͨɽࣜ(4)ΑΓɼsin[2πf t] ͱsin[2π(2f )t]૬खͷΛؚ·ͳ͍͜ͱ͕ Δɽ͜ͷੑ࣭Λʮޓ͍ʹަ͢ΔʯͱݺͿɽ ԋशI
֤ࣗͰcos[2πf t]ͱcos[2π(2f )t]ɼcos[2πf t]ͱ
sin[2πf t]ͷ߹ʹ͍ͭͯޓ͍ʹަ͢Δ͜ͱΛ ͔֬ΊΑʢඞཁͰ͋ΕΛࢀরʣɽ ͜͜Ͱͱͳͬͨͷʮࡾ֯ؔͷੵɾʯ ͷެ͕ࣜୈҰาͰ͋Γɼ͍֮͑ͯͳͯ͘Ճ๏ఆ ཧ͔Βಋग़Ͱ͖Δ͜ͱΛ͕͑ͨεϚϗͰެࣜΛ ௐΔֶੜ͕̍ʗ̏ఔډͨɽߋʹsin x, cos xͷ حؔɼۮؔʹ͍ͭͯͷࣝࣄલʹ͍ͬͯ ΔֶੜগͰ͋ΓɼͦΕΛ༻͍ͨ؆ུԽল͍ ͨɽͦͯ͠sin[±nπ] = 0 (n)Λ͍֮͑ͯ Δֶੜগͳ͔ͬͨɽΑͬͯ͜ΕΒͷ༰Λ ʹࡌͤΔ͜ͱͱͨ͠ɽ ʢҰ෦ʣ ࡾ֯ؔͷجຊެࣜ sin[−θ] = − sin θ, cos[−θ] = cos θ. ੵɹˠɹɾࠩ sin α cos β = 1 2{sin[α + β] + sin[α − β]} , cos α sin β = 1 2{sin[α + β] − sin[α − β]} , sin α sin β =−1 2{cos[α + β] − cos[α − β]} , cos α cos β = 1 2{cos[α + β] + cos[α − β]} . ಛผͳҰൠ֯ͷʢn, ʣ sin[nπ] = 0, cos[nπ] = (−1)n. ෆఆੵެࣜ xadx = 1 a + 1xa+1, (a= −1), adx = ax, eaxdx = 1 aeax, sin[ax]dx =−1 acos[ax], cos[ax]dx = 1 asin[ax],
ఆੵ b a f(x)dx = [F (x)]ba= F (b)− F (a), b a f(x)dx = − a b f(x)dx, c a f(x)dx = b a f(x)dx + c b f(x)dx, b a f(x) · g (x)dx = [f (x)· g(x)]b a − b a f(x)· g(x)dx. ͏ҰɼԋशIͷղ͕ʮੵ݁Ռ͕θϩʹ ͳͬͨʯͱ͜ΖͰࢭΊͯ͠·͏ֶੜ͕͍ۙ͘ ͨɽ͜ͷ՝ͷతަੑΛࣔ͢͜ͱͰ͋Γɼ ࠷ޙʹʮΑͬͯ***ͱ***ަ͢ΔɽʯͱͷҰจ Λॻ͘Α͏ʹࢦಋΛߦͬͨɽ 3 ϑʔϦΤڃల։ ަੑͷ֬ೝʹΑͬͯϑʔϦΤɼϑʔϦΤ ڃల։ͷઆ໌͕Մೳͱͳͬͨɽ࣮ݧॻʹҎԼ ͷ༰Λهͨ͠ɽ ϑʔϦΤ पظT ͷपظ৴߸f(t)༷ʑͳपΛ ͍࣋ͬͯΔɽ͔͠͠पf(= 1/T )[Hz]ͷ cos[2πf t]Λf(t)ʹֻ͚ͯੵͯ͠ಘΒΕ ͨྔa1ͱɼsin[2πf t]Λf(t)ʹֻ͚ͯੵͯ͠ ಘΒΕͨྔb1ͷΈͰ͋Δɽಉ༷ʹपmf[Hz] ʢmʣͷʹ͍ͭͯam, bmͱͯ͠ಘ ΒΕΔɽ am = 2 T T/2 −T/2f(t) · cos[2π(mf)t]dt, (5) bm = 2 T T/2 −T/2f(t) · sin[2π(mf)t]dt. (6) ͨͩ͠ɼੵͷલͷ2/T ਖ਼نԽͷͨΊɽ ͜ͷam, bmΛʮϑʔϦΤʯͱݺͼɼपظ৴ ߸f(t)ʹؚ·ΕΔcos[2πmf t]ͱsin[2πmf t]ͷ ৼ෯Λද͍ͯ͠Δɽ ϑʔϦΤڃల։ ϑʔϦΤ͕ٻΊΒΕΕपظ৴߸f(t)Ҏ ԼͷΑ͏ʹදݱͰ͖Δɽ f(t) = a0 2 + ∞ m=1 (amcos[2π(mf )t] +bmsin[2π(mf )t]) . (7) ্ࣜʹ͓͍ͯmແݶେ·Ͱ͠߹ΘͤΔඞཁ ͕͋Δ͕ɼ༗ݶͷmͰଧͪͬͯf(t)ʹۙ ͍ܗ͕ಘΒΕΔɽ ࣮ͦͯ͠ࡍʹϑʔϦΤΛٻΊΔԋशͱͯ͠ ҎԼͷԋशIIΛֶੜʹ՝ͨ͠ɽ ԋशII पظ T (ඞཁͰ͋ΕT = 10−3[sec.]) ͷۣܗ͘ ͚ ͍ ɼࡾ֯ͷ࣌ؒܗͦΕͧΕࣜ(8), (9)Ͱ ද͞ΕΔɽ·֤ͣ࣌ؒܗΛ࣮ݧϊʔτʹඳ͖ɼ ͦΕʹଓ͍ͯͦΕͧΕͷϑʔϦΤam, bmΛ m = 10·Ͱܭࢉ͢ΔʢඞཁͰ͋ΕΛࢀ রʣɽ • ۣܗ f(t) = 1 |t| ≤ T/4, −1 T/2 > |t| > T/4. (8) • ࡾ֯ f(t) = 4 Tt + 1 −T/2 ≤ t ≤ 0, −T4t + 1 0 < t < T/2. (9) ԋशIIͷղ๏ʹ͓͍ͯɼੵ۠ؒͷׂΛΠ ϝʔδ͠қ͘͢ΔͨΊʹ࣌ؒܗΛϊʔτʹॻ͔ ͤΔ͜ͱʹͨ͠ɽ͔͠͠ɼ͜͜Ͱʹͳͬͨͷ ઈରͷ֎͠ํΛΕ͍ͯΔֶੜׂ͕̔΄Ͳډ ͨ͜ͱͰ͋Δɽ͢ͳΘͪɼʮઈରͷத͕ਖ਼Ͱ ͋Εͦͷ··֎͠ɼෛͰ͋ΕϚΠφεΛ͚ ͯ֎͢ʯͱ͍͏͜ͱ͕࣮ߦͰ͖ͳֶ͍ੜ͕ଟ͔ͬ ͨɽ·ͨʮۣܗʯ͕ಡΊͳֶ͍ੜଟ͍ͨͨ ΊϧϏΛଧͭ͜ͱͱͨ͠ɽ ۣܗͷϑʔϦΤಋग़ެࣜΛݟͳ͕Β Εେ෦ͷֶੜ͕࣮ߦͰ͖ͨɽ͔͠͠ࡾ֯ͷ ߹෦ੵͷٕज़ʢʁʣ͕ඞཁͰ͋ΓɼҰൠ ͱͯ͠ͷެࣜʹࡌͤͯ͋Δɽ
ʢҰ෦ʣ ෦ੵ b a f(x) · g (x)dx (10) = [f (x)· g(x)]ba− b a f(x)· g(x)dx. ͔͠͠ɼͦΕΛ༻͍ͯ۩ମతʹੵΛ࣮ࢪͰ͖Δ ֶੜׂ̎ఔͰ͋ͬͨɽ࣮ࡍͷܭࢉɼࣜ(9) ΑΓҎԼͷखॱͰ͋Δɽ am = 2 T 0 −T/2 4 Tt + 1 cos[2π(mf )t]dx (11) +2 T T/2 0 −T4t + 1 cos[2π(mf )t]dx ͱ ͳ Δ ͷ t cos[2π(mf)t]dx Ͱ ͋ Γɼ f(t) = t, g(t) = cos[2π(mf )t]ͱஔ͍ͯܭࢉΛਐ ΊΔඞཁ͕͋Δɽ ͦͯ͠࠷ऴతʹϑʔϦΤΛҎԼͷදͷܗࣜ ʹ·ͱΊΔΑ͏ɼࢦࣔΛग़͕ͨ͠MS WordΛ༻ ͍ͨ࡞දʹ͕ଟੜͨ͡ɽ ද1: ϑʔϦΤͷ·ͱΊํ m 1 2 3 · · · 10 am · · · · bm · · · · MS Wordʹ͓͍ͯදΛ࡞͢ΔʹWordࣗ ͷػೳΛ͏߹ͱExcelͰ࡞දͨ͠ϞϊΛ WordʹషΓ͚Δ߹ͷ̎छྨͷํ๏͕͋Δɽ WordͰ࡞දͨ͠߹ʹʮࣜʯͳͲΛ༻͍ͯ ࣜه߸ΛೖྗͰ͖Δ͕Excel͔ΒషΓ͚Δ ߹ʹηϧʹʮࣜʯ͕ೖྗ͞ΕͣɼςΩετ ϘοΫεͱͯ͠ೝࣝ͞Εͯ͠·͏ɽΑͬͯWord ʹΑΔ࡞දΛࢦࣔͨ͠ɽ ·ͨOffice 2007Ҏ߱ͷWordʹଐͷʮࣜʯ Ͱཧతʹਖ਼͍͕ࣜ͠ॻ͖ͮΒ͘ɼϑΥϯτ͕ ࣼΊʢΠλϦοΫʣʹͳΔ߹ͱཱͭʢϩʔϚϯʣ ߹ͷ͕݅ෆ໌֬Ͱ͋ΔɽΑͬͯʮૠೖʯλϒ͔ ΒʮΦϒδΣΫτʯΛબͼɼʮMicrosoft ࣜ3.0ʯ ͷར༻ΛקΊͨɽ ֶੜͷதʹࣜπʔϧΛΘͣʹϑΥϯτα Πζͷมߋ͚ͩͰ্͖ɼԼ͖Λදͦ͏ͱͨ͠ ऀډͨɽ͔͠͠ಠཱࣜͱͷෆ౷ҰΛࢦఠ͠ɼ͢ ͯͷ߹ʹಉࣜ͡πʔϧΛ͏͜ͱΛࢦࣔ ͨ͠ɽ ͳ͓ɼΠλϦοΫͱϩʔϚϯͷॻ͖͚ʮม ΠλϦοΫʯɼʮఆϩʔϚϯʯͱͯ͠ࢦࣔ ग़͕ͨ͠ɼ࣮ݧॻʹ໌ه͠ͳ͔ͬͨɽ͜ͷล Γֶձݸਓͷߟ͑ํͰํ͕ҟͳΔ߹͕͋ ΔͨΊ໌จԽ͠ͳ͔ͬͨɽ 4 ExcelʹΑΔܗ߹ ͔͜͜Β2ͷ࣮ݧʹͳΔɽઌʹٻΊͨਖ਼ ݭͱࡾ֯ͷϑʔϦΤʹج͖ͮɼExcelͰ ඳ͍ͨߴपΛ͠߹ΘͤΔ͜ͱͰਖ਼ݭ ࡾ֯ʹ͍ۙܗ͕߹Ͱ͖Δ͜ͱΛ֬ೝ͢Δɽ ۩ମతʹҎԼͷखॱΛ࣮ݧॻʹهड़ͨ͠ɽ ExcelͷجૅࣝI ࿈ଓσʔλͷ࡞ʢAྻʹ1͔Β1000·Ͱͷ ΛೖΕΔʣ (1) A1ͷηϧΛબ͠ɼ“1”Λೖྗ ˎ ࣮ࡍͷೖྗ࣌ʹ“ɹ”ෆཁɽ (2) ӈͷεΫϩʔϧόʔͷ্෦ʹ͋ΔʮׂϘο ΫεʯΛϓϧμϯ͠ɼϫʔΫγʔτΛ্ Լʹׂ̎͢Δɽ (3) ԼଆͷϫʔΫγʔτΛεΫϩʔϧ͠ɼ1000 ߦۙΛදࣔͤ͞Δɽ (4) A1ͷηϧΛΫϦοΫ͠ɼʮSHIFTʯΩʔΛ ԡ͠ͳ͕ΒA1000ͷηϧΛΫϦοΫɽ ˎ ͜ΕͰA1͔ΒA1000·Ͱͷηϧ͕બ͞ ΕΔɽ (5) ʮϗʔϜʯλϒͷʮฤूʯˠʮϑΟϧʯˠ ʮ࿈ଓσʔλͷ࡞ʯΛબɽ (6) ʮ૿ʯ͕ʮ̍ʯͰ͋Δ͜ͱΛ֬ೝͯ͠ ʮ̤̠ʯɽ ͨͩ͠ϫʔΫγʔτΛׂ̎͢ΔʮׂϘοΫ εʯOffice2013Ҏ߱ແ͘ͳ͓ͬͯΓɼͦͷ ΘΓʹʮදࣔʯλϒ͔ΒʮΟϯυʯͷʮ
ׂʯΛબ͢Δඞཁ͕͋Δɽ ଓ͍ͯσʔλͷೖྗΛҎԼͷࢦࣔʹΑΓߦ͏ɽ ExcelͷجૅࣝII ࿈ଓσʔλͷ࡞ʢBྻͷ1͔Β1000·Ͱʹ −π͔Βπ·ͰͷΛۉʹೖΕΔʣ (1) B1ͷηϧΛબ͠ɼ “=A1*2*PI()/1000-PI()”ͱೖྗɽ ˎ ͜ͷ͕ࣜԿΛҙຯ͍ͯ͠Δ͔ߟ͑Δ͜ͱɽ (2) B1͔ΒB1000·ͰͷηϧΛબɽ (3) ʮϗʔϜʯλϒͷʮฤूʯˠʮϑΟϧʯˠ ʮԼํίϐʔʯΛબɽ (4) B1 ʹ-3.13531ɼͦ ͜ ͔ Β ૿ ͑ ͯ ͍ͬͯ B1000ʹ3.141593͕ೖ͍ͬͯΔ͜ͱΛ֬ ೝ͢Δɽ ExcelͷجૅࣝIII άϥϑͷ࡞ʢIʣ (1) B1ͷηϧΛΫϦοΫͯ͠ɼʮૠೖʯλϒ͔ Βʮάϥϑʯˠʮࢄਤʯˠʮࢄਤʢ ઢʣʯΛબɽ (2) ඞཁͰ͋ΕάϥϑΛΫϦοΫ͠ɼʮάϥϑ πʔϧʯͷʮσβΠϯʯλϒ͔Βʮσʔλʯ ˠʮσʔλͷબʯͰඞཁͳσʔλΛՃɼ আͰ͖Δɽ ˎ ʮσʔλൣғʯʹ “= Sheet1! $B$1 : $B$1000 ”ͱೖྗ͞Ε͍ͯΔɽಉ࣌ʹຌྫ ߲ͷʮฤूʯΛΫϦοΫ͢Εʮܥྻ̍ʯ ͳͲͱ͍ͬͯΔຌྫͷ༰มߋͰ͖Δɽ (3) ಉ༷ʹʮϨΠΞτʯλϒ͔Βॎ࣠ɼԣ࣠ ͷॻࣜɼϥϕϧͳͲ͕มߋͰ͖Δɽ Ҏ্ͷ݁Ռɼਤ1ΛಘΔɽ ͜͜ͰࢄਤΛ༻͍͕ͨɼֶੜંΕઢάϥ ϑΛબͼ͕ͨΔɽࢄਤͱંΕઢάϥϑͷҧ͍ ԣ࣠ͷબఆ͕Ͱ͖Δ͔Ͳ͏͔Ͱ͋Δɽ۩ମతʹ ද2ͷσʔλΛߟ͑ɼંΕઢάϥϑͱࢄਤʹ͠ ͯΈΔͱਤ2ͱਤ3ΛಘΔɽ͢ͳΘͪંΕઢάϥ ϑͷ߹ԣ࣠ৗʹ1, 2, 3, Ͱ͋Γɼͦͷதԝ ਤ1: ExcelͷجૅࣝI,II,III ʹϚʔΧʔ͕ݱΕΔɽͦͯ͠AྻͱBྻͦΕ ͧΕҟͳΔ̎ຊͷάϥϑʹͳΔɽҰํͰࢄਤʹ ͓͍ͯAྻΛԣ࣠ɼBྻΛॎ࣠ͱͯ͠ϚʔΧʔ ͕ଧͨΕΔɽ͢ͳΘͪy = f(x)ͷ༷ʹɼ༩͑Β Εͨxͷʹରͯ͠yͷ͕ఆ·Δ߹ʹࢄ ਤΛΘͳ͍ͱਖ਼͘͠ඳըͰ͖ͳ͍ɽΑ্ͬͯʹ ࣔͨ͠Α͏ʹૢ࡞खॱΛॻ͖ද͢͜ͱͰඞͣʮࢄ ਤʯΛબͿΑ͏ʹ͚ͨɽֶ͔͠͠ੜʮં Εઢʯʹऒ͔ΕΔΑ͏Ͱ͋Δɽ ද2: ExcelͰάϥϑΛඳͨ͘Ίͷσʔλྫ A B 1 0.1 1 2 0.2 2 3 0.3 3 4 0.4 4 5 0.5 5 6 0.6 6 7 0.7 7 8 0.8 8 9 0.9 9 10 1.0 10 ͦΕҎ֎ʹExcelͷάϥϑʹ͍͔ͭ͘ ͕͋Δɽ·ͣউखʹάϥϑͷλΠτϧΛਤͷத ʹॻ͘͜ͱͰ͋ΔɽιϑτΣΞαΠΤϯεֶՊ
0 2 4 6 8 10 12 1 2 3 4 5 6 7 8 9 10 ⣔ิ1 ⣔ิ2 ਤ2: ંΕઢͷ߹ 0 2 4 6 8 10 12 0 0.2 0.4 0.6 0.8 1 1.2 ⣔ิ1 ਤ3: ࢄਤͷ߹ Ͱʮਤ൪߸ɼλΠτϧਤͷԼʯͱࢦࣔΛͯ͠ ͍Δɽ͜Εࢲୡͷؔ͢ΔֶձͷதͰIEEE ͕ࢦͱ͓ͯ͠Γɼຊͷిࢠใ௨৴ֶձͦ Εʹ४͍ͯ͡Δ͜ͱΛड͚ͯͷࢦಋͰ͋Δɽͪͳ Έʹʮද൪߸ɼλΠτϧදͷ্ʯ͕Γجຊ Ͱ͋Δɽ͍ͣΕʹͯ͠ਤ൪߸ɼλΠτϧΛਤͷ தʹؚΊΔͷͰͳ͘ɼਤͱಠཱͯ͠Word Ͱૠೖ͖͢Ͱ͋Δɽ͜Εฤूաఔʹ͓͍ͯਤ ൪߸ɼλΠτϧͷมߋ͕ඞཁʹͳͬͨ߹ʹExcel ͳͲͷਤ·Ͱͬͯมߋ͢ΔͷͰͳ͘ɼWord ͷॲཧͰࡁ·ͤΔ͜ͱΛతͱ͍ͯ͠Δɽ·ͨɼ ਤʹλΠτϧ͕͘ͷͰҰຊ͔͠ઢ͕ແ͍߹ ຌྫʢʮܥྻ̍ʯͳͲʣඞཁͳ͍ɽߋʹExcel ԣ࣠ӈଆʹ༨നΛ͚ͯ͘ΕΔɽਤ3ͷ߹ࠨ ʹ0͔Β0.1·Ͱͷ༨ന͕͋Δ͔Βཱͨͳ͍͕ɼ ࠨ͔Βઢ͕Ҿ͔Ε͍ͯͯӈʹۭനʢਤ3Ͱ 1͔Β1.2ʣ͕ଘࡏ͠ɼόϥϯε͕ѱ͍ɽͰ ֶੜʮExcelͷग़ྗ͕͜͏ͳ͔ͬͨΒʯͱݴͬ ͯͦͷ··షͬͯ͘Δྫ͕ଟ͍ɽղܾͷͨΊʹ ԣ࣠ͷΛΫϦοΫͨ͠ޙɼϦϘϯͷʮάϥϑ πʔϧʯͷʮϨΠΞτʯλϒΛબ͠ɼࠨʹ͋ ΔʮબରͷॻࣜઃఆʯΛΫϦοΫ͢Εʮ࣠ ͷॻࣜઃఆʯ૭্ཱ͕͕ͪΓɼ࣠ͷΦϓγϣϯͰ ʮ࠷େʯΛ1.0ʹ߹ΘͤΕྑ͍ɽ ଓ͍ͯҎԼͷԋशΛߦ͍ɼߴपͷඳըͷ ४උΛߦ͏ɽ ԋशI CྻɼDྻͷͦΕͧΕͷ1ߦ͔Β1000ߦ ʹ−2π͔Β2πɼ−3π ͔Β3π·ͰͷΛۉ ʹೖΕΑɽ ͜ͷԋशʹ͓͍ͯ1࣍ؔy = ax + bͷy ยbͱ͖aΛߟ͑ͯؔΛೖྗͯ͠ཉ͔ͬ͠ ͕ͨɼؾֶ͍ͮͨੜC1ͷηϧʹ“=2*B1”ͱ ೖྗ͠ɼD1ͷηϧʹ“=3*B1”ͱೖྗ͍ͯͨ͠ɽ ࣍ʹɼಘΒΕͨྻͷΛ༻͍࣮ͯࡍʹ༨ݭ ʢجຊʣΛඳ͘ɽ ExcelͷجૅࣝIV άϥϑͷ࡞ʢIIʣ (1) E1ͷηϧΛબ͠ɼʮࣜʯλϒ͔Βʮؔ ϥΠϒϥϦʯͷʮֶʗࡾ֯ʯΛϓϧμ ϯ͠ɼʮCOSʯʢ߹ʹΑͬͯʮSINʯʣ Λબ͢Δɽ (2) ʮؔͷҾʯ૭͕։͍ͨΒʮB1ʯͱೖྗ ͠ʮOKʯɽ ˎ ݁Ռతʹ“ʹCOS(B1)”ͱೖྗ͞ΕΔɽ (3) E1͔ΒE1000·ͰͷηϧΛબɽ (4) ʮϗʔϜʯλϒͷʮฤूʯˠʮϑΟϧʯˠ ʮԼํίϐʔʯΛબɽ (5) E1ͷηϧΛΫϦοΫͯ͠ɼʮૠೖʯλϒ͔ Βʮάϥϑʯˠʮࢄਤʯˠʮࢄਤʢ ઢʣʯΛબɽ (6) ඞཁʹԠͯ͡ຌྫॎ࣠ɼԣ࣠Λݟ͘͢ มߋ͢Δɽ ࠷ޙͷ߲ʹ͓͚Δຌྫɼॎ࣠ɼԣ࣠ͷมߋ رͷ߲ΛΫϦοΫ͠ɼϦϘϯͷʮάϥϑπʔ ϧʯͷʮϨΠΞτʯλϒΛબ͠ɼࠨʹ͋Δ ʮબରͷॻࣜઃఆʯ͔ΒՄೳͱͳΔɽ ্هͷʮάϥϑͷ࡞ʢIIʣʯʹΑͬͯͰجຊ पظͷ༨ݭΛඳ͍ͨɽଓ͍ͯԋशIIͰৼ෯Λ มߋͨ͠ΓɼԋशIIIͰߴௐΛඳ͍ͨΓ͢Δɽ
ԋशII ্هͷखॱͰಘΒΕͨ༨ݭ(ίαΠϯ)ͷάϥ ϑͷৼ෯Λ̎ഒʹ͢Δํ๏Λߟ࣮͑ͯߦ͠ɼά ϥϑΛ࡞ͤΑɽ ͜Εࣜ(7)ʹ͓͚Δcos 2πmf tͷৼ෯Λam ͱ͢Δ४උͰ͋Δɽ ԋशIII ʮExcelͷجૅࣝIVʯͰಘΒΕͨ༨ݭͷά ϥϑ1͔Β1000·ͰΛҰपظͱ͢Δ༨ݭ cos[2πf t]Ͱ͋Δɽ͢ͳΘͪԣ࣠Λ࣌ؒͱ͠ɼͦ ͷʮ1ʯ͔Βʮ1000ʯ·ͰΛ10−3[sec.]ͱݟͳ ͢ͱप1kHzͷ༨ݭ͕ඳ͚ͨ͜ͱʹͳΔɽ (1) ͜ͷάϥϑͷԣ࣠Ͱt = 0ʹରԠ͢ΔҐஔ Ͳ͔͜ɼߟ͑Αɽ (2) ԋशIͷ݁ՌΛར༻ͯ͠प͕m(= 2, 3, · · · , 10)ഒͷ༨ݭcos[2π(mf )t]ͷάϥϑ ࡞ͤΑɽ ͜͜ͰߴௐͷάϥϑΛ࡞͢Δ͕ɼઌͷ ંΕઢάϥϑͱࢄਤͰઆ໌͕ͨ͠ಉ༷ʹى ͜Δɽ͢ͳΘͪɼଟ͘ͷֶੜm = 1, 2, · · · , 10 ͷσʔλΛExcelͷྻʹฒͯάϥϑͷ४උΛ͢ Δɽ͔͠͠ࠨͷྻʹm = 1ͷσʔλ͕ೖͬͯ ͓ΓɼͦΕ͕Excelʹʮx࣠ͷʯͰ͋Δͱஅ ͞Εͯ͠·͏ɽͦͷ݁ՌɼಘΒΕΔάϥϑ͕ਤ4 ͷΑ͏ʹͳͬͯ͠·͏͜ͱ͕ଟ͍ɽͪͳΈʹਖ਼ղ ਤ5ͷΑ͏ʹΔ͖Ͱ͋Δɽ͢ͳΘͪɼબ ͢Δσʔλͷࠨʹx࣠ʹରԠ͢ΔΛೖΕ͓ͯ ͘ඞཁ͕͋Δɽͳ͓͜ͷྫͰx࣠Λ1͔Β1000 ·Ͱͱ͕ͨ͠ɼ࠲ඪมΛͯ͠−0.5͔Β0.5ʹ ͠ɼ୯ҐΛ[ms]ͱ͢Ε1kHzͷपظ৴߸Λѻͬ ͍ͯΔ͜ͱͱͳΔɽ͜ͷ࠲ඪม࣮ݧ։࢝ॳɼ ֶੜʹٻΊ͕ͨҙຯΛཧղ͢Δֶੜ͕গͳ͔ͬͨ ͨΊɼ͔̏Βֶੜʹ՝͞ͳ͘ͳͬͨɽ ·ͨɼਤ4ɼ5ʹ͓͍ͯຌྫ͕ʮܥྻ1ɼܥྻ 2ɼɾɾɾʯͱͳ͍ͬͯΔ͕વɼมߋ͖͢Ͱ͋Δɽ ͦΕมߋ͍ͨ͠άϥϑΛબͨ͠ޙɼʮάϥϑ πʔϧʯͷʮσβΠϯʯλϒ͔Βʮσʔλͷબʯ ΛΫϦοΫ͠ɼࠨʹ͋Δʮຌྫ߲ʯͷத͔Βر ͷσʔλΛબͼʮฤूʯϘλϯΛԡ͢͜ͱͰر ͷจݴʹมߋ͠ɼ̤̠Λԡ࣮ͤݱͰ͖Δɽ ͦͯ͠߹ܗͱൺֱ͢ΔͨΊʹݩͷ࣌ؒܗ -1.5 -1 -0.5 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 ⣔ิ1 ⣔ิ2 ⣔ิ3 ⣔ิ4 ⣔ิ5 ⣔ิ6 ⣔ิ7 ⣔ิ8 ⣔ิ9 ਤ 4: ߴௐͷඳըʢࣦഊྫʣ -1.5 -1 -0.5 0 0.5 1 1.5 0 200 400 600 800 1000 ⣔ิ1 ⣔ิ2 ⣔ิ3 ⣔ิ4 ⣔ิ5 ⣔ิ6 ⣔ิ7 ⣔ิ8 ⣔ิ9 ⣔ิ10 ਤ 5: ߴௐͷඳըʢޭྫʣ ԋशIVͱͯ͠ඳ͔ͤͨɽ ԋशIV ࣜ(8), (9)Ͱࣔ͞Εۣͨܗɼࡾ֯ͷ࣌ؒ ܗ1͔Β1000ΛҰपظͱͯ͠ExcelͰ࡞ ͤΑɽ ͜ͷ߹ۣܗ༰қʹඳ͚Δ͕ࡾ֯ख ͣ͜Δֶੜ͕ଟ͔ͬͨɽ͢ͳΘۣͪܗͷ߹ ʮ1͔Β250·Ͱ−1ɼ251͔Β750·Ͱ1ɼͦ͠ ͯ751͔Β1000·Ͱʹ−1ʯΛೖྗ͢Εඳ͚ Δɽ͔͠͠ࡾ֯ͷ߹ʮ1ͷͱ͖ʹ−1(+α)ɼ ͔ͦ͜Β1࣍ؔͱͯ͠૿Ճ͠ɼ500ͷͱ͖ʹ1ɽ ͦͯ͠Ұ࣍ؔͱͯ͠ݮগ͠1000ͷͱ͖ʹ−1ʯ ͱͳΔඞཁ͕͋ΔɽͦͷͨΊ1͔Β500·Ͱʹ “=2*A1/500-1”ͳͲͱೖྗ͠ɼ501͔Β1000· Ͱʹ“=(-2)*A501/500+3”ͳͲͱೖྗ͢Δඞ ཁ͕͋ΔɽࣗͰ͜ΕΛߟ͑ͯೖྗͰֶ͖ͨੜ ະຬͰ͋ͬͨɽ ͜͜·Ͱͷ४උ͕ऴΘͬͯɼ͍Α͍Αܗ߹ ͷ࣮ݧͰ͋Δɽ ࣮ݧ༰ 1) पظT ͷۣܗɼࡾ֯ͷϑʔϦΤ͘ ͚ ͍ ʢam, bm, m = 0, 1, 2, · · · , 10ʣطʹٻΊ
ͯ͋Δɽ 2) ԋश III Ͱ࡞ͨ͠༨ݭ cos[2π(mf )t] ʢm = 0, 1, 2,· · · , 10ʣͷ ৼ ෯ Λ ϑ ʔ Ϧ Τ am ʹ ม ߋ ͠ ɼExcel ্ ʹ amcos[2π(mf )t]ͷσʔλΛ४උ͢Δɽ ˌ ඞཁͰ͋Εbmsin[2π(mf )t]ͷσʔλ ४උ͢Δɽ 3) ࣜ(7)ͷϑʔϦΤڃల։Λ༗ݶͷप ʢM = 5, 10ʣ·Ͱ͠߹Θͤͨ߹ ʹಘΒΕΔܗf(t)͕ݩͷ࣌ؒܗf(t) ʹ͍͔ۙͲ͏͔ΛExcelͰάϥϑʹͯ͠؍ ͢Δɽ f(t) = a0 2 + M m=1 (amcos[2π(mf )t] +bmsin[2π(mf )t]) . (12) ˌ M ͷҧ͍͕߹͞Εͨܗf(t)ʹͲ͏Ө ڹ͢Δ͔ཧղ͢Δɽ ͜ͷ࣮ݧ༰Λॲཧ͢Δखॿ͚ͱͯ࣍͠ͷجૅ ࣝܝࡌͨ͠ɽ ExcelͷجૅࣝV M m=1xm(= x1+ x2+· · · + xM)ͷܭࢉ (1) Mm=1xmͷ݁ՌΛೖྗ͍ͨ͠ηϧΛબ ͢Δɽ (2) ʮࣜʯλϒ͔ΒʮؔϥΠϒϥϦʯͷʮ ֶʗࡾ֯ʯΛϓϧμϯ͠ɼʮSUMʯΛબ ͢Δɽ (3) ʮؔͷҾʯ૭͕։͍ͨΒɼʮ̍ʯʹ x1ͷ͕ೖ͍ͬͯΔηϧɼʮ̎ʯʹx2 ͷ͕ೖ͍ͬͯΔηϧɼͱͯ͠xM ͷ͕ ೖ͍ͬͯΔηϧ·ͰΛॱ࣍બ͢Δɽ (4) ʮOKʯΛԡ͢͜ͱʹΑͬͯܭࢉ݁Ռ͕࠷ ॳͷηϧʹදࣔ͞ΕΔɽ ˎ ඞཁͰ͋ΕʮԼํʹίϐʔʯ্ͯ͠ه ͷܭࢉΛԼͷηϧʹөͤ͞Δɽ ͜ΕʹΑͬͯݩͷܗɼ߹ʢM = 5, 10ʣ ͷάϥϑ͕ग़དྷ্͕Δɽ·ͣظ͞ΕΔ݁ՌΛ ਤ6ͱਤ7ʹࣔ͢ɽ -1.5 -1 -0.5 0 0.5 1 1.5 0 200 400 600 800 1000 M=5 M=10 ▴ᙧἼ ਤ6: ۣܗͷ߹ܗͱݩܗ -1.5 -1 -0.5 0 0.5 1 1.5 0 200 400 600 800 1000 M=5 M=10 ୕ゅἼ ਤ7: ࡾ֯ͷ߹ܗͱݩܗ ͜͜·Ͱͷάϥϑ࡞Ͱྑ͘ݟΒΕͨΤϥʔ ɼۣܗͷϑʔϦΤ͕શͯਖ਼ͷʹͬͯ ͓Γ߹͕ෆࢥٞͳܗʹ͍ͬͯΔ߹͕͋Δɽ Τϥʔάϥϑʹ׳Εͯ͘Δͱʮ͜ͷਤܗ͜ͷΤ ϥʔʯͱஅͰ͖ΔΑ͏ʹͳΔɽ·ͨࡾ֯ͷ ߹ʹΤϥʔͰͳ͍͕̏ຊͷઢ͕΄΅ॏͳΔͨ Ίɼάϥϑͷଠ͞લޙͷॱ൪Λ͢Δ͜ͱͰ ݟ͍͢άϥϑ͕࡞Ͱ͖Δɽ ·ͨCݴޠͷϓϩάϥϜʹΑͬͯϑʔϦΤ amͱcos[2π(mf )t]ͷΛܭࢉ͠ɼࣜ(12)ʹ ͓͍ͯM = 2030ͷ߹ͷσʔλΛٻΊΔ͜ ͱՄೳͰ͋Δɽͦͯ͠csvܗࣜͰϑΝΠϧग़ྗ ͠ɼExcelͰಡΈࠐΉ͜ͱʹΑͬͯਤ6ɼ7ͱॏͶ ͯඳ͘͜ͱՄೳͰ͋ΔɽϓϩάϥϜྫΛҎԼʹ ࣔ͢ɽ #include <stdio.h> #include <math.h> int main(void) {
double sum,am; double pi = 3.14159265; int i,m; FILE *fp; fp=fopen("data1.csv","w"); for(i=1;i<=1000;i++){ sum=0; for(m=1;m<=30;m++){ am=4.0/(pi*m)*sin(pi*m/2.0); printf("%d,%f\n",m,am); sum=sum +am*cos(m*(2.0*pi *i/1000.0-pi)); } fprintf(fp,"%d,%f\n",i,sum); } fclose(fp); return 0; } ࣮ࡍʹϓϩάϥϜͰσʔλΛ࡞ͬͯάϥϑʹࡌͤ ֶͨੜ͕աڈʹ໊ډΔɽ ͜ΕΒͷ༰͕֬ೝͰ্͖ͨͰൃలԋशͱͯ͠ ҎԼͷ༰Λهͨ͠ɽ ൃలԋशI ҎԼʹࣔ͢ܗʹ͍ͭͯϑʔϦΤΛಋग़ ͠ɼͦͷৼ෯ͷਖ਼ݭʢ͘͠༨ݭʣΛ ্͛͠Δ͜ͱʹΑͬͯݩͷܗ͕࠶ݱ͞ΕΔ͜ ͱΛ֬ೝͤΑɽ • Ұपظ͕࣍ࣜͰఆٛ͞ΕΔۣܗ f(t) = −1 −T/2 ≤ t < 0, 1 0≤ t < T/2. (13) • Ұपظ͕࣍ࣜͰఆٛ͞ΕΔܗʢf = 1/Tʣ f(t) = cos2πf t + π 4 , −T/2 < t < T/2. (14) ൃలԋशII ݩͷ࣌ؒܗf(t)ͱࣜʢ12ʣʹج͍ͮͯ߹ ͞Εͨܗf(t)ͱͷࠩҟ͕Ͳͷఔ͋Δͷ͔ ΛͦΕͧΕͷܗʹ͍ͭͯͰࣔͤɽ • ࠩҟΛٻΊΔҰྫͱͯ͠|f(t) − f(t)|ͷੵ ɼ͢ͳΘͪ −T/2T/2 |f(t) − f(t)|dtͰධՁ Ͱ͖Δɽ • ࣮ࡍʹExcel্Ͱ֤࣌ࠁtiʹରԠ͢Δ ࢄతσʔλΛͦΕͧΕf(ti)ͱf(t i)ͱ͠ ͯಘ͍ͯΔͷͰ1000i=1 |f(ti)− f(ti)|Λܭ ࢉ͢ΕΑ͍ɽ • ্هͱҟͳΔධՁํ๏ʹ͍ͭͯߟ͑ͯ ΈΑɽ ೦ͳ͕ΒൃలԋशIΛղֶ͘ੜ1ʹҰਓ ͔ೋਓɼൃలԋशIIʹࢸͬͯաڈ10΄Ͳͷ ؒʹยखͰΓΔ͔͠ଘࡏ͠ͳ͔ͬͨɽಛʹ͜ ͷ5΄ͲօແͰ͋Δɽ 5 ·ͱΊ ιϑτΣΞαΠΤϯε࣮ݧͰߦ͖ͬͯͨϑʔ ϦΤղੳͷमಘඪͱͦͷ࣮ݧ༰Λࣔͨ͠ɽ֤ ߲Ͱੜ͡ΔͱͦΕʹର͢Δղܾࡦʹ͍ͭ ͯ۩ମతʹࣔͨ͠ɽ͜ΕΒͷ༰͕কདྷͷֶੜ࣮ ݧɼ͘͠ϑʔϦΤղੳͷߨٛʹཱͭͱ͍ Ͱ͋Δɽ ࢀߟจݙ [1] ࢁɼफ૾ษɼࢁ࡚ߒҰɼখߊɼେ࡚ ਖ਼༤ɼιϑτΣΞαΠΤϯε࣮ݧ̞ࢦಋॻɼ ୈ̍൛ɼ20099݄11 [2] ࢁɼफ૾ษɼࢁ࡚ߒҰɼখߊɼେ࡚ ਖ਼༤ɼιϑτΣΞαΠΤϯε࣮ݧ̞ࢦಋॻɼ 2013൛ɼ20139݄18 ݄̎̌̍̒̎̎̕ݪߘड Received, February 29, 2016 ݄̎̌̍̒̐̍ݪߘमਖ਼ Revised, April 1st, 2016 2016 年2月 29 日原稿受付,2016 年3月 14 日採録決定 Received, February 29, 2016; accepted, March 14, 2016