Frequently Asked Questions

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brunato
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Joined: 2010-07-22

 Here is a list of Frequently Asked Questions and their corresponding answer.

  1. Is 4A/OP free ?
  2. On what computer platforms will the code run ?
  3. Is the code stable ?
  4. Is there a GUI (Graphical User Interface) ?
  5. Does 4A/OP plot the results ?
  6. I'm having a problem with using the GUI: I have an error when I launch the GUI. Is there any easy way to debug this ?
  7. How much memory and disk space does it require ?
  8. What are the recent changes ?
  9. What future enhancements are planned ?

 

    1. Is 4A/OP free ?

          Yes, 4A/OP is provided free of charge under the GNU General Public License. All we ask is that you acknowledge it appropriately in any publications that result from its use. See the Reference Documentation for details on how to reference the software (Referencing 4A/OP in publications).

    2. On what computer platforms will the code run ?

          The code is written in Fortran 90 so it will run on any computer that has a Fortran 90 compiler. Moreover, a new routine written in C has been introduced and needs that a C compiler is installed on your system. Makefiles are provided for a number of Unix platforms. 4A/OP has been compiled and tested on Sun (Sparc Solaris) and Linux PC environments. See the Reference Documentation for more information.

    3. Is the code stable ?

          4A has been used for a number of years by scientists working in a variety of research areas. While it would not be wise to guarantee that the model is bug-free, no serious problems have been reports for the last two or three years.

    4. Is there a GUI (Graphical User Interface) ?

          Yes, there is a GUI that can be used to set up and run 4A/OP. The 4A/OP GUI needs that Tcl/Tk (at least version 8.4) and Gnuplot (at least version 4.0) are installed on your system. The GUI is particularly useful for new users.

    5. Does 4A/OP plot the results ?

          Yes, 4A/OP can plot the results if you use the GUI and if Gnuplot (at least version 4.0) is installed on your system.

    6. I'm having a problem with using the GUI: I have an error when I launch the GUI. Is there any easy way to debug this ?

          Yes. That means that either a bad version of Tcl/Tk is installed or Tcl/Tk is not installed. You need to install Tcl/Tk at least version 8.4. You also need that Gnuplot (at least version 4.0) is installed.

    7. How much memory and disk space does it require ?

          The 4A executable occupies only less than one megabyte on disk. It uses about 200 megabytes of memory. The associated files (sources and user input files) occupy about 25 megabytes of disk space. There are also the atlas files that require about 6.5 gigabytes of disk space. This volume depends on the user simulation needs.
          The size of the output files is a function of the input simulation parameters, which you control.

    8. What are the recent changes?

          See the Release notes history.

    9. What future enhancements are planned ?

          A way to accelerate the computing time in case of the use of 4AOP with DISORT is in progress.