iscrn - a switch to plot the parameter adjustments and updated velocity model to the screen (default: 1) dmpfct - an overall damping factor to control the trade-off between resolution and variance (default: 1.0) velunc - an estimate of the uncertainty (square root of the variance) of the model velocity values (km/s) (default: 0.1; however, if velunc is equal to zero, the uncertainties listed in the file i.out are used) bndunc - an estimate of the uncertainty (square root of the variance) of the depth of model boundary values (km) (default: 0.1; however, if bndunc is equal to zero, the uncertainties listed in the file i.out are used) xmax - maximum distance (km) of velocity model (default: none)