#When running fringe-fit with the 'workshop-branch' CASA version, failed solutions occur with the following type of message in the CASA logger:
"""
2019-06-20 05:56:55	INFO		Antenna 3 correlation 1 has (FFT) SNR of 3294.43.
2019-06-20 05:56:55	INFO		Starting least squares optimization.
2019-06-20 05:56:55	INFO		Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least squares complete for correlation 1 after 3 iterations.
2019-06-20 05:56:55	INFO		Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least-squares solver failed to converge; flagging
2019-06-20 05:56:55	INFO	+	Least squares complete for correlation 0 after 3 iterations.
2019-06-20 05:56:55	INFO		Antenna 1 correlation 0 has (FFT) SNR of 22683.
"""

#Using casa-release-5.4.0-68.el7, the fringe-fitter processes the data without issues

fringefit(vis="synth.ms/",caltable="test.t",field="",spw="",intent="",selectdata=True,timerange="2017/04/11/10:38:55~2017/04/11/10:39:36",antenna="",scan="",observation="",msselect="",solint="3.5s",combine="",refant="AA",minsnr=3.0,zerorates=False,append=False,docallib=False,callib="",gaintable=[],gainfield=[],interp=[],spwmap=[],parang=False)