RAYMUL

First Step

Before you proceed to the example below, you should have read another article on RAYPP to understand the earth model to be used.

Multiple Definitions

To produce the travel-times of any kind of multiples, what you need to do is just defining the multiple indices which is based on the figure below :

From the figure, the multiple on the left can be defined as the following integer series :

imult = [1 1 1 1]';

The multiple on the right can be written as :

imult = [1 2 2 2 2 1]';

Hence, you can change the type of your multiples simply by arranging the indices.

Procedure

To run the program RAYMUL you have to go through the steps below :

• Install Scilab on your computer.
• Download the program, and keep it in a directory of your choice. Let us assume that you put the file in directory /home/yourname/seislib.
  The size of the program is approximately 4.6 Kb.
• Write an ASCII file that contains commands to create the earth model, do ray tracing, and plot the travel-time curve. You can then modify the file to create new earth models to produce new travel-time curves. As an example, call the text editor, type the following lines, and save the lines in a file named exam1.sci in the directory you like.

  // Linking
  nmu = link('raymul.o','raymul','f');
  
  // Model
  vp    = [1000 2000 2500]';
  d     = [100 200 250]';
  x     = [0:50:500]';
  nmul  = 2;
  imul1 = [1 1 1 1]';
  lmul1 = length(imul1);
  imul2 = [1 2 2 2 2 1]';
  lmul2 = length(imul2);
  
  // Ray tracing
  nl  = mini([length(vp) length(d)]);
  ns  = length(x);
  tm1 = fort("raymul",vp,1,"r",d,2,"r",nl,3,"i",...
       imul1,4,'i',lmul1,5,'i',x,6,"r",ns,7,"i",...
       "out",[1,ns],8,"r");
  tm2 = fort("raymul",vp,1,"r",d,2,"r",nl,3,"i",...
       imul2,4,'i',lmul2,5,'i',x,6,"r",ns,7,"i",...
       "out",[1,ns],8,"r");
  tm  = [tm1 ; tm2];
  
  // Plotting
  st = ones(1,nmul);
  xbasc();
  plot2d1("onn",x,tm',st,"021");
  xtitle('Multiple reflections','Offset (meter)','Waktu (detik)');
  xend();
  

• Go to directory that contains file exam1.sci and call Scilab by typing scilab in xterm.
• Type the following command in the Scilab command window :

  exec('exam1.sci')
  

• You'll be given the travel-times (matrice tm) and the figure below :