A Fortran IV program uses cross correlation to determine the relative displacement and stretch factor between two time series. The program is applicable in correlating geophysical logs from two wells which have been digitized at equal intervals. The data are made stationary by filtering before cross correlation and stretching in the frequency domain. After iteratively stretching and cross correlating the logs, the maximum value of a normalized cross correlation function identifies the optimum stretch and lag (displacement). Output includes a line-printer list of the maximum correlation values and lags for all stretches and a calcomp plot of the original logs with tielines connecting equivalent zones. The program can also correlate two pairs of logs at one time by summing two cross correlation functions to reinforce the correlation process.