Hey,
I understand you are getting an indexing error while writing a code for the DIF-FFT algorithm.The problem here is, in the third iteration, the value of the variable “stage” is 3 and k1 and k2 will have two values each. But in the nested loop, x(k1(3)) and x(k1(4)) are accessed. Another thing is the value inside k2 will be greater than eight, which is higher than the length of the sequence.
Refer to the MATLAB code attached below.
x = input("enter the sequence");
N = length(x); % Length of sequence
p=log2(N); % computing the number of conversion stages
Half=N/2; % half the length of the array
for stage=1:p % stages of transformation
for index=0:(N/(2^(stage-1))):(N-1) % series of "butterflies" for each stage
for n=0:(Half-1) % creating "butterfly" and saving the results
pos=n+index+1; % index of the data sample
pow=(2^(stage-1))*n; % part of power of the complex multiplier
w=exp((-1i)*(2*pi)*pow/N); % complex multiplier
a=x(pos)+x(pos+Half); % 1-st part of the "butterfly" creating operation
b=(x(pos)-x(pos+Half)).*w; % 2-nd part of the "butterfly" creating operation
x(pos)=a; % saving computation of the 1-st part
x(pos+Half)=b; % saving computation of the 2-nd part
end
end
Half=Half/2; % computing the next "Half" value
end
y=bitrevorder(x);
Hope this will solve your problem.
