an error during IDA analysis ('CentralDifference', revertToStart())

[hadelcivil]

Hi,
I am trying to run a simple IDA analysis, which is a parallel set of 4 uniaxial materials. I put here the code related to IDA and also the error which occurred.

ops.wipeAnalysis() # clear previously-define analysis parameters
ops.constraints('Lagrange') # how it handles boundary conditions
ops.numberer('Plain') # renumber dof's to minimize band-width (optimization), if you want to
ops.system('BandGeneral') # how to store and solve the system of equations in the analysis
ops.algorithm('Linear') # use Linear algorithm for linear analysis

ops.integrator('CentralDifference') # determine the next time step for an analysis # determine the next time step for an analysis
ops.analysis('Transient')


# Analysis duration and time step
dt = dt
Nsteps = nPts

# Arrays for plotting
Uplot = []
gmPlot = []

# Maximum and increment in ground motion factor
maxGM = 2
dgm = 0.05

gmFact = 0.0
while gmFact < maxGM:

gmFact += dgm
gmPlot.append(gmFact)

ops.remove('loadPattern',1)

ops.reset()

# Redefine ground motion with new factor
#ops.pattern('UniformExcitation',1,1,'-accel',1,'-factor',gmFact)
ops.pattern('UniformExcitation', 1, 1, '-accel', 2,'-factor',gmFact)

# Perform analysis and record maximum displacement
Umax = 0
for i in range(Nsteps):
ops.analyze(1,dt)
U = ops.nodeDisp(2,1)
if abs(U) > Umax:
Umax = abs(U)

Uplot.append(Umax)

ERROR:
ERROR: revertToStart() method not yet implemented
for the chosen type of integrator.