IFOS2D (Inversion of Full Observed Seismograms) is a 2-D elastic full waveform inversion code.
The inversion problem is solved by a conjugate gradient method and the gradients are computed in the time domain by the adjoint state method.
The forward modeling is done by a time domain Finite-Difference scheme.
IFOS2D is the reverse (inverse) of our 2-D Finite-Difference forward solver SOFI2D.
The manual is included in the download archive or can be downloaded here.
Release: 
You can download the latest Release 2.0.3 or the current Beta-Version.
To receive news and updates please register on the email list IFOS@lists.kit.edu.
Please use this list also to ask questions or to report problems or bugs.