/* An array of complex values is stored as an array of pairs of floats,
   each pair consisting of the real part followed by the imaginary part.
   The array can be 1-D or 2-D, and the lengths of the first and second
   axes are given by nx and ny respectively.
*/
typedef struct {
	int allocated;		/* true if memory has been allocated */
	float *data;		/* 1-D or 2-D array of data */
	int nx, ny;		/* size of array of data */
	float *workx, *worky;	/* scratch space used by FFT routines */
} CmplxArray;

/* real and imaginary parts of a complex 1-D array */
# define RPIX1D(z,i) ((z)->data[2*i])
# define IPIX1D(z,i) ((z)->data[2*i+1])

/* real and imaginary parts of a complex 2-D array */
# define RPIX2D(z,i,j) ((z)->data[2 * (i + (z)->nx * j)])
# define IPIX2D(z,i,j) ((z)->data[2 * (i + (z)->nx * j) + 1])

/* complex array memory management */
void InitCmplxArray (CmplxArray *);
int AllocCmplxArray (CmplxArray *, int, int);
void FreeCmplxArray (CmplxArray *);

/* forward and inverse Fourier transforms of 2-D complex arrays */
int fft2d (CmplxArray *);
int ifft2d (CmplxArray *);

/* utility functions for complex arrays */
void FFTShift (CmplxArray *);
void CpyCmplx (CmplxArray *, CmplxArray *);

/* These are the Fourier transform functions written by Paul Swarztrauber. */
# if defined(NO_UNDERSCORE)
# define FTDREC_U ftdrec
# define CFFTI cffti
# define CFFTF cfftf
# define CFFTB cfftb
# else
# define CFFTI cffti_
# define CFFTF cfftf_
# define CFFTB cfftb_
# endif

void CFFTI (int *, float *);
void CFFTF (int *, float *, float *);
void CFFTB (int *, float *, float *);