Hello Stanislav, Here is the first sample problem I would like you to write a fortran program to solve. In the file ~hammett/stanislav/tftr.dat.Z is some simulated data based on fluctuation spectra measured in TFTR by the Beam Emission Spectroscopy diagnostic. To convert the file to a readable format, copy the file to your directory, and type: uncompress tftr.dat.Z You can look at the resulting file by typing "more tftr.dat". I would like you to write a program to read in this data, calculate the 2-point correlation functions C(dx) and C(dy) (the correlation between two points separated by a distance dx (at the same y) or by a distance dy (at the same x), averaged over the whole box). I.e., C(dx) = where the average <...> is a simple integral (or summation) over all (x,y). This program should also make a plot of C(dx) and C(dy), overlayed on the same scale, using the ncar plotting subroutine library. Also calculate the Kurtosis of the field: K = /**2 - 3 The Kurtosis should be near zero if phi has Gaussian statistics... To help you get started, here are the fortran statements used to create the tftr.dat data file, which you can turn into equivalent read statements to read the data into your program: c write out density(x,y) to a simple file: open(unit=21,file='tftr.dat',status='unknown') write(21,*) mx, ' = # of x grid points ' write(21,*) my, ' = # of y grid points ' write(21,*) 'x grid:' write(21,*) (x(i),i=1,mx) write(21,*) 'y grid:' write(21,*) (y(i),i=1,my) write(21,*) 'Phi(x,y):' write(21,*) ((den(i,j),i=1,mx),j=1,my) close(unit=21) **************************************************************************** Once you have this code working on the tftr.dat file, you should then run it on the data in ~hammett/stanslav/tftr2.dat.Z, and you should find some interesting differences... Once you can do the above, we can move on to working directly with the gyrofluid simulation code. Greg