1. Lecture 1 : January 2001 Dr. Andrew Paul Myers
FORTRAN 77 Programming.
Lecture 1 : January 2001
Dr. Andrew Paul Myers
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2. Course Methods. Lectures. Handout notes. Supervised practical work.
Daily submission of exercises.
Daily feedback on exercises.
Model Answers.
Final project.
Weekly clinic for final Project.
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3. Introduction. A course in FORTRAN 77. Why FORTRAN? Objectives :
General education in computing.
Introduction to programming.
First write a simple program, then…
Write complex program.
Course Benefits :
I.T. is a part of all our lives and getting more so!
FORTRAN and computing skills for other courses.
Future employment.
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4. Tools For The Job. Programming Environment :
CFS system and Exceed 6.2.
Unix system (SG IRIX 6.5).
Silicon Graphics Desktop
Windows Text Editor (emacs).
FORTRAN 77 Compiler (Mips 7.2.1).
Workshop Debugger (cvd).
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5. Programming Languages.
You are users!
How computers work.
Machine code.
High level languages.
Fortran : FORMula TRANslation.
Other languages :
Basic
C/C++
Pascal
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6. Programming Cycle. Analyse the task.
Plan the program, a structured approach!
Flowcharts & Dry running.
Edit your source code.
Compile and link program.
Execute and debug program.
Edit and recompile as necessary.
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7. IRIX f77 Compiler.
Edit source program (*.f) with “emacs” editor. Save file.
Compile and run on Unix command line in a shell window :
/disk/n/gps> f77 –o test test.f
/disk/n/gps> test
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8. Simple Structure of A FORTRAN Program.
Program name.
Declare variables and structures.
Assign values to variables.
Process data.
Print results.
End program.
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9. Flow of a Program. Linear sequence. One command per line.
Position on line : Very Important!
Comments Statements (ignored).
Repetition : Loops.
Selections : Conditional statements.
Always finish with an END statement.
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10. Position on a line.
The layout of FORTRAN program dates back to old 80 column punched cards, which were used for program input. 1
2-5 6
7-72
73-80
Total=x_value+y_value
&
+z_value C
Comment line. 9
9999
FORMAT(‘Answer =‘,I4)
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11. Variable Declarations.
Variable names :
Must be at least one alphabetic character long, up to a maximum of 31 alphanumeric characters.
Must start with an alphabetic character. Case insensitive.
Alphanumeric characters are : a-z, 0-9 and the underscore ( _ ).
Implicit variables. I to N integers!
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12. Examples. Valid names : Invalid names : X THEDAY Min_cur Time28 X*Z
THE TIME
7YEARS
_no_way$
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13. Basic Data Types. REAL x=5.0 INTEGER i=20 COMPLEX z=(1.4,3.2)
LOGICAL test=.TRUE.
CHARACTER char=‘Hello’
More advanced data types can be made from these basic types.
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14. Declarations.
<Data Type> <variable> [,<variable(s)>]
e.g.
REAL x
REAL radius,volume
INTEGER loop,temp
CHARACTER string*10,name*30
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15. Parameters.
Parameters are constants, their value, once defined, can not be changed.
REAL g,pi
INTEGER days
PARAMETER (days=365)
PARAMETER (g=9.81,pi=3.142)
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16. Assignments. radius=2.5 y=z test=value+loop-temp
<variable> = <value> | <variable> | <expression>
radius=2.5
y=z
test=value+loop-temp
volume=(4.0*pi*radius**3.0)/3.0
Expressions follow the BODMAS precedence rule. Operators +, -, *, / and **
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17. Control Structures. Basic building blocks of programs.
They control the flow of the program.
There are 3 different types :
Linear Sequence.
Selection.
Iteration or Loop.
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18. Other Statements. PROGRAM [ program name ] END C or * A comment.
PRINT*,’Hello’
PRINT*,’Value of X = ‘,x
This is free format output.
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19. Data Input. Programs are useless without data!
Use the READ statement to allow users to input data.
Prompt user for the data too!
e.g.
PRINT*,’Enter values for x & y :’
READ*,x,y
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20. Character Input.
A normal read statement can not be used to enter character variables. Use the following:
PRINT*,’Continue (y/n) : ‘
READ ‘(A1)’,yes_or_no
‘(A<n>)’ – <n> is the number of characters.
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21. Good Programming Style.
Comment your program!
FORTRAN keywords in upper case.
Variables in lower case.
Use descriptive variable names.
Blanks may be used to improve readability.
Indent code with “tabs”.
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22. General Program Layout.
PROGRAM [ program name ]
[ comments ]
[ declaration statements ]
[ executable statements ]
STOP
END
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23. References. A Crash Course in FORTRAN 77. Donald M. Monro.
(Edward Arnold).
Irix Insight On-line Help.
SGI Developer Section.
MIPSpro FORTRAN 77 Programmer’s guide.
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