% FAST FOURIER TRANSFORM ALGORITHM 8.3
%
% To compute the coefficients in the discrete approximation
% for the data (x(J),y(J)), 0<=J<=2m-1 where m=2^p and
% x(J)=-pi+J*pi/m for 0<=J<=2m-1.
%
% INPUT: m; y(0),y(1),...y(2m-1).
%
% OUTPUT: complex numbers c(0),...,c(2m-1); real numbers
% a(0),...,a(m); b(1),...,b(m-1).
syms('OK', 'FLAG', 'M', 'N', 'JJ', 'J', 'Y', 'A');
syms('NAME', 'INP', 'F', 'Z', 'OUP', 'TW', 'N2', 'C');
syms('NG', 'NU1', 'YY', 'WW', 'X', 'W', 'K', 'L', 'M1');
syms('NP', 'T1', 'T3','x','s');
TRUE = 1;
FALSE = 0;
fprintf(1,'This is the Fast Fourier Transform.\n\n');
fprintf(1,'The file IBR.m is used by this program.\n');
fprintf(1,'The user must make provisions if the\n');
fprintf(1,'interval is not (-pi,pi).\n');
OK = FALSE;
while OK == FALSE
fprintf(1,'Choice of input method:\n');
fprintf(1,'1. Input entry by entry from keyboard\n');
fprintf(1,'2. Input data from a text file\n');
fprintf(1,'3. Generate data using a function F\n');
fprintf(1,'Choose 1, 2, or 3 please\n');
FLAG = input(' ');
if FLAG == 1 | FLAG == 2 | FLAG == 3
OK = TRUE;
end;
end;
if FLAG == 1
OK = FALSE;
while OK == FALSE
fprintf(1,'Input m\n');
M = input(' ');
if M > 0
OK = TRUE;
N = 2*M;
Y = zeros(1,N);
for JJ = 1 : N
J = JJ-1;
fprintf(1,'Input y(%d).\n', J);
Y(JJ) = input(' ');
end;
else
fprintf(1,'Number must be a positive integer.\n');
end;
end;
end;
if FLAG == 2
fprintf(1,'Has a text file been created with the ');
fprintf(1,'entries y(0),...,y(2m-1)\n');
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