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A very efficient length N = 11 FFT module that can be use alone or with the PFA or the WFTA. Designed by Howard Johnson in 1981.

N=11 fft module

A FORTRAN implementation of a length-11 FFT module to be used in a Prime Factor Algorithm program.

C DATA C111,C112 / 1.10000000, 0.33166250 /DATA C113,C114 / 0.51541500, 0.94125350 / DATA C115,C116 / 1.41435370, 0.85949300 /DATA C117,C118 / 0.04231480, 0.38639280 / DATA C119,C1110/ 0.51254590, 1.07027569 /DATA C1111,C1112/ 0.55486070, 1.24129440 / DATA C1113,C1114/ 0.20897830, 0.37415717 /DATA C1115,C1116/ 0.04992992, 0.65815896 / DATA C1117,C1118/ 0.63306543, 1.08224607 /DATA C1119,C1120/ 0.81720738, 0.42408709 / CC-----------------WFTA N=11---------------------------- C111 T1 = X(I(2)) + X(I(11)) T6 = X(I(2)) - X(I(11))T2 = X(I(3)) + X(I(10)) T7 = X(I(3)) - X(I(10))T3 = X(I(4)) + X(I(9)) T8 = X(I(4)) - X(I(9))T4 = X(I(5)) + X(I(8)) T9 = X(I(5)) - X(I(8))T5 = X(I(6)) + X(I(7)) T10= X(I(6)) - X(I(7))C U1 = Y(I(2)) + Y(I(11))U6 = Y(I(2)) - Y(I(11)) U2 = Y(I(3)) + Y(I(10))U7 = Y(I(3)) - Y(I(10)) U3 = Y(I(4)) + Y(I(9))U8 = Y(I(4)) - Y(I(9)) U4 = Y(I(5)) + Y(I(8))U9 = Y(I(5)) - Y(I(8)) U5 = Y(I(6)) + Y(I(7))U10= Y(I(6)) - Y(I(7)) CT11 = T1 + T2 T12 = T3 + T5T13 = T4 + T11 + T12 T14 = T7 - T8T15 = T6 + T10 CU11 = U1 + U2 U12 = U3 + U5U13 = U4 + U11 + U12 U14 = U7 - U8U15 = U6 + U10 CAM0 = X(I(1)) + T13 AM2 = (T14 - T15 - T9) * C112AM3 = (T2 - T4) * C113 AM4 = (T1 - T4) * C114AM5 = (T2 - T1) * C115 AM6 = (T5 - T4) * C116AM7 = (T3 - T4) * C117 AM8 = (T5 - T3) * C118AM11 = (T12 - T11) * C1111 AM14 = (T6 + T7) * C1114AM17 = (T8 - T10) * C1117 AM20 = (T14 + T15) * C1120C AN0 = Y(I(1)) + U13AN2 = (U14 - U15 - U9) * C112 AN3 = (U2 - U4) * C113AN4 = (U1 - U4) * C114 AN5 = (U2 - U1) * C115AN6 = (U5 - U4) * C116 AN7 = (U3 - U4) * C117AN8 = (U5 - U3) * C118 AN11 = (U12 - U11) * C1111AN14 = (U6 + U7) * C1114 AN17 = (U8 - U10) * C1117AN20 = (U14 + U15) * C1120 CS0 = AM0 - C111 * T13 S7 = AM11 + C1110 * (T1 - T3)S8 = AM11 + (T2 - T5) * C119 S9 = AM14 + (T6 - T9) * C1113S10 =-AM14 + (T7 + T9) * C1112 S11 = AM17 + (T8 - T9) * C1116S12 =-AM17 + (T9 - T10) * C1115 S13 = AM20 + (T6 - T8) * C1119S14 =-AM20 + (T7 + T10) * C1118 CV0 = AN0 - C111 * U13 V7 = AN11 + C1110 * (U1 - U3)V8 = AN11 + (U2 - U5) * C119 V9 = AN14 + (U6 - U9) * C1113V10 =-AN14 + (U7 + U9) * C1112 V11 = AN17 + (U8 - U9) * C1116V12 =-AN17 + (U9 - U10) * C1115 V13 = AN20 + (U6 - U8) * C1119V14 =-AN20 + (U7 + U10) * C1118 CS15 = S0 + S7 + AM7 + AM8 S16 = S0 - S7 - AM4 - AM5S17 = S0 + S8 + AM6 - AM8 S18 = S0 - S8 - AM3 + AM5S19 = S0 + AM3 + AM4 - AM6 - AM7 S20 = S13 + AM2 + S11S21 = S13 - AM2 - S9 S22 = S14 + AM2 + S12S23 = S14 - AM2 - S10 S24 = S9 + S10 + S11 + S12 - AM2C V15 = V0 + V7 + AN7 + AN8V16 = V0 - V7 - AN4 - AN5 V17 = V0 + V8 + AN6 - AN8V18 = V0 - V8 - AN3 + AN5 V19 = V0 + AN3 + AN4 - AN6 - AN7V20 = V13 + AN2 + V11 V21 = V13 - AN2 - V9V22 = V14 + AN2 + V12 V23 = V14 - AN2 - V10V24 = V9 + V10 + V11 + V12 - AN2 CX(I(1)) = AM0 X(I(2)) = S19 + V24X(I(3)) = S15 + V20 X(I(4)) = S16 + V21X(I(5)) = S17 - V22 X(I(6)) = S18 + V23X(I(7)) = S18 - V23 X(I(8)) = S17 + V22X(I(9)) = S16 - V21 X(I(10))= S15 - V20X(I(11))= S19 - V24 CY(I(1)) = AN0 Y(I(2)) = V19 - S24Y(I(3)) = V15 - S20 Y(I(4)) = V16 - S21Y(I(5)) = V17 + S22 Y(I(6)) = V18 - S23Y(I(7)) = V18 + S23 Y(I(8)) = V17 - S22Y(I(9)) = V16 + S21 Y(I(10))= V15 + S20Y(I(11))= V19 + S24 CGOTO 20 CFigure. Length-11 FFT Module

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Source:  OpenStax, Large dft modules: 11, 13, 16, 17, 19, and 25. revised ece technical report 8105. OpenStax CNX. Sep 14, 2009 Download for free at http://cnx.org/content/col10569/1.7
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