Inverse Fourier synchrosqueezed transform

inverts
the synchrosqueezed transform along the time-frequency ridges specified
by the index vector or matrix `x`

= ifsst(`s`

,`window`

,`iridge`

)`iridge`

. If `iridge`

is
a matrix, then `ifsst`

initially performs the inversion
along the first column of `iridge`

and then proceeds
iteratively along the subsequent columns. The output is a vector or
matrix with the same size as `iridge`

.