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# Program 1: Goertzel Algorithm

Module by: C. Sidney Burrus. E-mail the author

Summary: Goertzel Algorithm

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## Goertzel Algorithm

A FORTRAN implementation of the first-order Goertzel algorithm with in-order input as given in ((Reference)) and [1] is given below.

 C---------------------------------------------- C GOERTZEL'S DFT ALGORITHM C First order, input inorder C C. S. BURRUS, SEPT 1983 C--------------------------------------------- SUBROUTINE DFT(X,Y,A,B,N) REAL X(260), Y(260), A(260), B(260) Q = 6.283185307179586/N DO 20 J=1, N C = COS(Q*(J-1)) S = SIN(Q*(J-1)) AT = X(1) BT = Y(1) DO 30 I = 2, N T = C*AT - S*BT + X(I) BT = C*BT + S*AT + Y(I) AT = T 30 CONTINUE A(J) = C*AT - S*BT B(J) = C*BT + S*AT 20 CONTINUE RETURN END 

## References

1. Burrus, C. S. and Parks, T. W. (1985). DFT/FFT and Convolution Algorithms. New York: John Wiley & Sons.

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