Icfftcalculates the discrete inverse Fourier transform of the sequence in the array F and stores the result in the arrayA.Lognis the base-2 log of the number of points in the sequences. The arraysAandFmust contain at least 2Lognelements; if they have more than this number of elements, the extra elements are ignored and unmodified. The number of elements denoted by each permitted value ofLognis shown in the table below:
Logn No. Elements (2Logn)
2 4
3 8
4 16
5 32
6 64
7 128
8 256
9 512
10 1024
11 2048
12 4096
13 8192
14 16384
The meaning of the values input toIcfftis the same as that for the values output by theCfftroutine; see the entry for theCfftroutine for a detailed explanation of the meaning of the values input toIcfft.
Errors
Icfftcauses an HTBasic error if its arguments are not of the types shown in the USAGE section, above, ifLognis not between 2 and 15, inclusive, or if the size ofAorCis smaller than 2Logn.