HOW TO BUILD A PROGRAMMING PROJECT





BUILDING A F90 PROJECT

/home/joeusr

aero361/

 labs

lab #[1-14, or some name]

src/     dat/       bin/  report/
 All projects need to follow the directory structure similar to the one shown on the left. Every f90 project should have the four basic files named as
main.f90
 main program
 contains the main program
input.f90
 subroutine input()
 used only for input
output.f90
 subroutine output()
 used for post-processing of results
solver.f90
 subroutine/function solver
 calls all other subroutines that are used to model the math. The other subroutines are your choice. Name them appropriately.
global.f90
 module global
 Using a global Module. Will come in handy when doing the panel project

QUICK GUIDE

ATTENTION

Download source files for practice into the src/dir. Yes you can overwrite the files you created in the previous step using the touch command.

THE PROBLEM

  • The purpose of this lab is to understand the steps required when creating and executable from a set of source files.
The problem being solved in this code is a simple volume plot represented with spherical contour lines in 3 dimensions
w = z^2 + y^2 + x^2
This exercise will cover the following
  1. Creating and accessing Modules
  2. Creating and destroying Allocatable arrays
  3. passing variables through the procedure argument lists
  4. assigning names to Open file statements
    • Reading from a file
    • Writing to a file with simple formatting
  5. Accessing procedures from the main program
  6. Get a taste of Tecplot and the wonderful world of post processing

THE SOURCE FILES

The set of source files listed below should be downloaded and saved in the src/ directory of lab1/. Do not change the names of the files. If you notice there is a global.f90 files included in this set, the global.f90 file is a module file which is treated the same way as other .f90 source files, but is accessed in a different way.

input.dat (store this in the bin/ directory)
main.f90
input.f90
solver.f90
output.f90
global.f90

MODULE FILE: global.f90

The module file is compiled and linked the same way as any main program or procedure files, except its function is different. This is a simple introduction to the concept of globals that will be detailed in a later lab. At the moment the introduction to the module file is sufficient. Any file that accesses the module will have access to the variables and arrays in the module file. This mitigates the use of long and cumbersome argument lists specially when variables and arrays are being used in more than one procedure (subroutine, function and main program). Here is a small and concise example

module global
implicit none
save
integer :: variable1,variable2
integer,parameter :: parameter1=#

Real(kind=8) :: variable3,variable4
Real(kind=8),dimension(1:parameter1,1:parameter1) :: array1,array2
Real(kind=8),allocatable,dimension(:,:) :: array3
end module global

program main
 use global
implicit none

end program main

For further reading refer to the index

HOW TO CREATE THE EXECUTABLE

This set of files will be used to appreciate the necessary steps involved in building and executable out of a set of source files. Whether you are programming in C, C++ or f90 the compile and link step will be involved.
COMPILE STEP
The compile step involves the compiler to check for language conformity. All the compile step does is check whether the proper syntax is being used and the contents of the source code is not in violation of any rules in the language. When the compile step is successful a set of object files is created. Before you compile these files as shown below there is one little catch when modules are involved. A module creates a dependency that needs to be clarified. When main.f90 accesses a module (global.f90) and its contents the information required to successfully compile main.f90 is contained in global.f90, therefore global.f90 needs to compiled before main.f90. In this case all the files require information stored in global.f90 and that is why global.f90 is compiled 1st.

NOTE: You should be in the src/ dir


<bash> ifc -c -w global.f90 main.f90 solver.f90 output.f90 input.f90
  • -c stands for the compile only flag
  • -w stands for ignore all warnings
LINK STEP
The object file cannot be read like a source file. The link step uses the object file to connect all the procedures and access all the system libraries from which an executable is created. The executable is when all the object files link together successfully.

<bash> ifc global.o main.o solver.o output.o input.o -o ../bin/code.x
  • -o stands for the user defined executable output flag
RUNNING THE code.x
The executable code.x will be located in ../bin directory. To run the executable the following command is used

NOTE: You should now be in the bin/ dir

<bash> cd ../bin
<bash> ./code.x

Whenever a script or a program executable needs to be executed one needs to prepend the name with a period ("."). Later on we will set it such that its done for you.

FINAL SOLUTION

The final solution should be a volume plot with spherical contour lines is as shown below. Till next lab play with this code create some errors and fix them. You can also play with the "tecplot" program and get comfortable with it. We will be assigning a lab specifically for tecplot, but i figured i might as well give you a taste of this cool package that us CFD people love to use.

NOTE: You should now be in the dat/ dir

<bash> cd ../dat
<bash> tecplot10 output.dat

















AFTER LAB ASSIGNMENTS

You will be expected to practice and read supplemental material prior to the next lab. Failure will result in incompetence and lack of understanding of future material.
  1. Read through the following page and get comfortable with the code development procedure: Quick guide to Projects
  2. Before your next lab clean up your /home/joeusr directory so that it looks neat and organized (click here)
  3. Spend the time getting used to the shell and the desktop items. Play with the customization and become comfortable launching the shell.