REM nm6bbc.bas - jackord@kw.igs.net - 16 Feb 08 - BBC Basic v5.50b
      REM FFSS coefficients for Pulse A and Pulse B
      REM   on a n-segment string clamped at both ends
      
      *FLOAT64
      INSTALL @lib$+"WINLIB5"
      
      REM Initialize Window
      b1% = FN_button("Pulse A", 92, 5, 60, 20, FN_setproc(PROCp1), 0)
      b2% = FN_button("Pulse B", 162, 5, 60, 20, FN_setproc(PROCp2), 0)
      c1% = FN_combobox("", 232, 5, 70, 120, 0, 3)
      WindowWidth=392
      WindowHeight=260
      VDU 23,22,WindowWidth;WindowHeight;8,15,16,128
      SYS "SetWindowText", @hwnd%, "Pulse on an N-Segment String"
      SYS "SendMessage", c1%, &143, 0, "n=48"
      SYS "SendMessage", c1%, &143, 1, "n=96"
      SYS "SendMessage", c1%, &143, 1, "n=192"
      SYS "SendMessage", c1%, &143, 1, "n=384"
      SYS "SendMessage", c1%, &14E, 0, 0
      DIM y(384): DIM v(384): DIM yy%(384)
      DIM b(64): DIM d(64): DIM w(64)
      kk=0: plt=0
      OFF: VDU 5
      
      REPEAT
        WAIT 1
      UNTIL FALSE
      QUIT
      
      DEF PROCp1: kk=1                         : REM Pulse A
      
      DEF PROCp2: kk=2                         : REM Pulse B
      
      SYS "SendMessage", c1%, &147, 0, 0 TO ch1%
      n=48*2^ch1%: s=0
      IF n=48 THEN nm=n ELSE nm=64
      FOR i=0 TO n
        y(i)=0: v(i)=0
      NEXT i
      FOR i=3*n/8 TO 5*n/8
        z=(i-3*n/8)*PI/(n/8)
        y(i)=40*(1-COS(z))
        v(i)=-40*PI/(n/8)*SIN(z)
        IF kk=2 THEN
          v(i)=v(i)*COS(4*z)+y(i)*4*PI/(n/8)*SIN(4*z)
          y(i)=y(i)*COS(4*z)
        ENDIF
      NEXT i
      FOR i=1 TO nm-1
        b(i)=0: d(i)=0: w(i)=2*SIN(PI*i/2/n)
        FOR j=1 TO n-1
          b(i)=b(i)+2*y(j)*SIN(PI*i*j/n)/n
          d(i)=d(i)+2*v(j)/w(i)*SIN(PI*i*j/n)/n
        NEXT j
        s=s+b(i)*b(i)+d(i)*d(i)
      NEXT i
      CLS: GCOL 0: LINE 16, 504, 16, 16: DRAW 768, 16
      GCOL 9
      FOR i=1 TO nm-1
        yy%(i)=INT(2400*(b(i)*b(i)+d(i)*d(i))/s+1)
        IF yy%(i)>1 THEN RECTANGLE FILL 16+12*i-4, 16, 10, yy%(i)
      NEXT i
      k=0: z=0
      WHILE z/s<.9999
        k=k+1: z=z+b(k)*b(k)+d(k)*d(k)
      ENDWHILE
      GCOL 12: MOVE 16, 16
      IF n=48 THEN nm=288 ELSE nm=384
      FOR i=n/48 TO nm STEP nm/48
        DRAW 16+2*i, 16+INT(4.8*n*SIN(i*PI/12/n)+1)
      NEXT i
      GCOL 0: MOVE 160, 430: PRINT "For Nmax = "; k
      MOVE 400, 430: PRINT "Percent = "; INT(100000*z/s)/1000
      ENDPROC