Homework #4

Due October 15?, 2009

Download the accompanying file called rays.txt from the website. rays.txt

It contains a table of six columns. Read the table into IDL. Make each column an array variable. Call them x,y,z,qx,qy,qz. Calculate the average of x and of y and then calculate x-x_av and y-y_av. Plot x-x_av vs y-y_av with the point symbol to show the scatter diagram of values. Save the plot to postscript.

Then truncate each array to its first 25 elements. Use idl to print a new data file of columns. Call it rays_av.txt. Read it into Excel. Use Exel to plot the values of x-x_av vs y-y_av.

Submit your IDL procedures, your .ps file, your .txt file and your .xls file to Will.