mlib_SignalIFFT_4(3MLIB)				    mediaLib Library Functions					  mlib_SignalIFFT_4(3MLIB)

NAME

       mlib_SignalIFFT_4,  mlib_SignalIFFT_4_S16_S16,  mlib_SignalIFFT_4_S16C_S16C,  mlib_SignalIFFT_4_S16_S16C,  mlib_SignalIFFT_4_S16, mlib_Sig-
       nalIFFT_4_S16C - signal Inverse Fast Fourier Transform (IFFT)

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_SignalIFFT_4_S16_S16(mlib_s16 *dstr, mlib_s16 *dsti,
	    const mlib_s16 *srcr, const mlib_s16 *srci,
	    mlib_s32 order, mlib_s32 *scale);

       mlib_status mlib_SignalIFFT_4_S16C_S16C(mlib_s16 *dstc,
	    const mlib_s16 *srcc,
	    mlib_s32 order, mlib_s32 *scale);

       mlib_status mlib_SignalIFFT_4_S16_S16C(mlib_s16 *dstr,
	    const mlib_s16 *srcc,
	    mlib_s32 order, mlib_s32 *scale);

       mlib_status mlib_SignalIFFT_4_S16(mlib_s16 *srcdstr,
	    mlib_s16 *srcdsti,
	    mlib_s32 order, mlib_s32 *scale);

       mlib_status mlib_SignalIFFT_4_S16C(mlib_s16 *srcdstc,
	    mlib_s32 order,
	    mlib_s32 *scale);

DESCRIPTION

       Each of the functions in this group performs Inverse Fast Fourier Transform (IFFT).

       The following equation is used for forward FFT:

		   1   N-1
	 dst[k] = ---- SUM {src[n] * exp(-j2*PI*n*k/N)}
		   C1  n=0

       and the following equation is used for inverse FFT (IFFT):

		   1   N-1
	 dst[n] = ---- SUM {src[k] * exp(j2*PI*n*k/N)}
		   C2  k=0

       where

	 k = 0, 1, ..., (N - 1)
	 n = 0, 1, ..., (N - 1)
	 N = 2**order

       The signal FFT/IFFT functions can be categorized into four groups according to the ScaleMode in the function names in the following form:

	 mlib_Signal[FFT|IFFT]_ScaleMode_OutType_InType_OpMode()
	 mlib_Signal[FFT|IFFT]_ScaleMode_DataType_OpMode()

       The scaling factors C1 and C2 used in the equations are defined as follows:

	   o	  For ScaleMode = 1, C1 = 1 and C2 = 2**order.

	   o	  For ScaleMode = 2, C1 = 2**order and C2 = 1.

	   o	  For ScaleMode = 3, C1 = C2 = 2**(order/2) when order is even, or C1 = 2**((order+1)/2) and C2 = 2**((order-1)/2) when  order	is
		  odd.

	   o	  For ScaleMode = 4, C1 = 2**P and C2 = 2**Q, where P and Q are adaptive scaling factors and are generated by the functions.

       For  functions  with  only  real  parts for the source signal, the imaginary parts are assumed to be all zero. For functions with only real
       parts for the destination signal, the imaginary parts are discarded. The functions with only one data type in their names perform the oper-
       ation in place.

PARAMETERS

       Each function takes some of the following arguments:

       dstr	  Destination signal array that contains the real parts.

       dsti	  Destination signal array that contains the imaginary parts.

       srcr	  Source signal array that contains the real parts.

       srci	  Source signal array that contains the imaginary parts.

       dstc	  Complex destination signal array. dstc[2*i] contains the real parts, and dstc[2*i+1] contains the imaginary parts.

       srcc	  Complex source signal array. srcc[2*i] contains the real parts, and srcc[2*i+1] contains the imaginary parts.

       srcdstr	  Source and destination signal array that contains the real parts.

       srcdsti	  Source and destination signal array that contains the imaginary parts.

       srcdstc	  Complex  source  and	destination  signal array. srcdstc[2*i] contains the real parts, and srcdstc[2*i+1] contains the imaginary
		  parts.

       order	  Order of the transformation. The base-2 logarithm of the number of data samples.

       scale	  Adaptive scaling factor.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_SignalFFT_1(3MLIB), mlib_SignalFFT_2(3MLIB),  mlib_SignalFFT_3(3MLIB),  mlib_SignalFFT_4(3MLIB),  mlib_SignalIFFT_1(3MLIB),  mlib_Sig-
       nalIFFT_2(3MLIB), mlib_SignalIFFT_3(3MLIB), attributes(5)

SunOS 5.11							    2 Mar 2007						  mlib_SignalIFFT_4(3MLIB)