User`s guide

IFFT
5-236
The block output is invalid if you set this parameter when the input is not
conjugate symmetric.
Inputs in Bit-Reversed Order
When the block input is in bit-reversed order, you must set the parameter
Input is in bit-reversed order to get a valid output. The block output is invalid
if you set this parameter when the input is not in bit-reversed order. A common
source of bit-reversed inputs is the FFT block, as illustrated in the FFT block
example, “Use of Outputs in Bit-Reversed Order” on page 5-179.
For a definition of bit-reversed and linear order, see the FFT block reference
page section, “Description of Bit-Reversed Ordering” on page 5-177.
Selecting the Twiddle Factor Computation Method
The FFT block and IFFT block both have a parameter, Twiddle factor
computation
. Setting this parameter in the IFFT block is very similar to
setting it in the FFT block. For details, see the FFT block reference page
section, “Selecting the Twiddle Factor Computation Method” on page 5-177.
Optimizing the Table of Trigonometric Values
The FFT block and IFFT block both have a parameter, Optimize table for.
Setting this parameter in the IFFT block is very similar to setting it in the FFT
block. For details, see the FFT block reference page section, “Optimizing the
Table of Trigonometric Values” on page 5-178.
Algorithms Used for IFFT Computation
Depending on whether the block input is real- or complex-valued and conjugate
symmetric, the block uses one or more of the following algorithms as
summarized in the next table:
•Radix-2 decimation-in-time (DIT) algorithm
•Half-length algorithm
•Double-signal algorithm