{VERSION 5 0 "IBM INTEL NT" "5.0" } {USTYLETAB {CSTYLE "Maple Input" -1 0 "Courier" 0 1 255 0 0 1 0 1 0 0 1 0 0 0 0 1 }{CSTYLE "" -1 256 "" 1 18 0 0 0 0 0 1 0 0 0 0 0 0 0 0 } {PSTYLE "Normal" -1 0 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }1 1 0 0 0 0 1 0 1 0 2 2 0 1 }{PSTYLE "Normal" -1 256 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }3 1 0 0 0 0 1 0 1 0 2 2 0 1 }} {SECT 0 {EXCHG {PARA 256 "" 0 "" {TEXT 256 55 "Animation of the Fourie r Analysis of a \"Saw-Tooth\" Wave" }}{PARA 0 "" 0 "" {TEXT -1 55 " \+ The fuction to study is F(t) = t for -1 < t < 1 " }}{PARA 0 "" 0 " " {TEXT -1 118 " The coefficients for the sine components of the \"S aw tooth\" wave are complicated (switching signs and magnitudets)." }} {PARA 0 "" 0 "" {TEXT -1 85 " m=number of terms to keep - then we \+ create a \"sequence\" of the sums (myseqsum) :" }}{PARA 0 "" 0 "" {TEXT -1 68 " first term of the sequence is just the first f ourier term" }}{PARA 0 "" 0 "" {TEXT -1 119 " second term of the sequence is the sum of the first two terms, third in sequence is \+ sum of first three terms" }}{PARA 0 "" 0 "" {TEXT -1 74 " Thus, we c an watch the final waveform evolve into the \"Saw Tooth\" Wave." }} {PARA 0 "" 0 "" {TEXT -1 135 " Also, we could create a sequence of j ust the fourier terms (myseq2) - we can see the amplitude of each succ essive term gets smaller." }}{PARA 0 "" 0 "" {TEXT -1 139 " \+ [ Once the \"graphs\" are created, click once on th e graph to highlight it, and you will see \"player controls\" " }} {PARA 0 "" 0 "" {TEXT -1 91 " appear i n a toolbar above - to let you run the animation.]" }}{PARA 0 "" 0 "" {TEXT -1 151 " Notice that as the \"SawTooth\" wave evolves .. there is some \"ringing\" at the discontinuities .. this is called Gibb's P henomena - no matter how many" }}{PARA 0 "" 0 "" {TEXT -1 141 " \+ terms you take, you can't get rid of it (at least not the over-ringing .. you can reduce the oscillations after that with more terms)." }} {PARA 0 "" 0 "" {TEXT -1 104 " Also, we can see here that the \"ov ershoot\" is more pronounced when there is a larger discontinuity " }} {PARA 0 "" 0 "" {TEXT -1 100 " (note the ringing \+ near the 2 unit drops vs the ringing near the 1 unit drops!)" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 21 "restart; with(plots):" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 32 "m:=20: # Number of terms to \+ keep" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 68 "mycoeff := seq( (-8 *(-sin(n*Pi)+n*Pi*cos(n*Pi))/(n^2*Pi^2)),n=1..m);" }}{PARA 0 "> " 0 " " {MPLTEXT 1 0 0 "" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 80 "myseq := seq( (-8*(-sin(n*Pi)+n*Pi*cos(n*Pi))/(n^2*Pi^2))*sin(n*Pi*x/2),n=1 ..m):" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 47 "myseqsum := seq(su m(myseq[nn],nn=1..n),n=1..m):" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 147 "display(seq(plot(myseqsum[i], x=-5..5,color=blue, thickness=2), i=1..m), insequence=true, title=`Evolution of Fourier series \+ to SawTooth`);" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 268 "# Note: Watch the discontinuities .. the series will never fully match the S awTooth because of the discontinuity ... that \"ringing\" at the corne rs is called the Gibb's Phenomena! And, the ringing is more pronounce d depending on how strong the discontinuity step is!" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 31 "myseq2 := seq(myseq[n],n=1..m):" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 161 "display(seq(plot(myseq2[i], x=-5..5,color=blue, thickness=2),i=1..m), insequence=true, t itle=`Individual terms of the Fourier series for the SawTooth`);" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}}{MARK "11" 0 } {VIEWOPTS 1 1 0 1 1 1803 1 1 1 1 }{PAGENUMBERS 0 1 2 33 1 1 }