# Subtract a piecewise-linear function from traces ('detrend') # # Here, we assume that 'top' and 'bottom' are trace headers containing # times of two horizons. The following will subtract from trace values # a function equal (constant) trace(top) above the time='top', linearly changing to # trace(bottom) at time='bottom', and constant to the bottom of the trace. *call trcmath detrend top =trc= bottom =trc=