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FORTRAN 77

FORTRAN 77. Presented by: Destry Diefenbach. The Free Online Dictionary of Computing ( http://foldoc.doc.ic.ac.uk/ ) Fortrash

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FORTRAN 77

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  1. FORTRAN 77 Presented by: Destry Diefenbach

  2. The Free Online Dictionary of Computing (http://foldoc.doc.ic.ac.uk/) Fortrash <abuse, language> /for'trash/ Hackerism for the Fortran language, referring to its primitive design, gross and irregular syntax, limited control constructs, and slippery, exception-filled semantics. [Jargon File] (1994-10-26)

  3. “Algol is FORTRAN done right.” -Bruce Knobe, 1973 • “Pascal is FORTRAN done right.” -Raymond Langsford, 1980 • “FORTRAN 77 is FORTRAN done right.” -James Ball, 1983

  4. History of FORTRAN • Stands for IBM Mathematical FORmula TRANslation System but abbreviated to FORmula TRANslation • FORTRAN 0 was developed by a IBM research team headed by John Backus in 1954. • Was the first high-level programming language John Backus 1924-1988

  5. More History • The design of FORTRAN made it easier to translate mathematical formulas into code. • FORTRAN originally began as a digital code interpreter for the IBM 701 • At that time it was called Speedcoding • The point of FORTRAN was to make programming easier. IBM 701

  6. FORTRAN I 1957 • Was the first compiler • By 1958 over 50% of software was in FORTRAN • Cut development time. • 2 weeks to 2 hours

  7. FORTRAN II - IV • FORTRAN II • Independent compilation • Fix the bugs • FORTRAN III • Was developed, but it was never widely distrbuted • FORTRAN IV • Explicit type declarations • Logical selection (IF) statement • Subprogram names could be parameters • ANSI standard in 1966

  8. FORTRAN 77 • FORTRAN 77 replaced FORTRAN IV as the new standard. • It retained most of the features of IV • It added • Character string handling • Logical loop control statements • And a If with a optional else statement

  9. Data Types FORTRAN 77 explicitly permits data types of integer, real, double precision, complex, logical, and characters.

  10. Real Data Types • Represent decimal numbers • It uses scientific notation • 3E5 300000 • .123E-3 .000123

  11. Double Precision Data Types • Instead of E it used D • 1D2 100

  12. Complex Data Types • Built in complex number data type • Which occupies 2 bytes • The first byte in the pair represents the real part of the complex data type. • The second byte represents the imaginary part of the complex item. represented as follows Numeric Value (4.61,-6.81) 4.61 – 6.81i (-10,5) -10+5i

  13. Program Structure • A FORTRAN program is a collection of subprogram definitions. • Subprograms may be a FUNCTION that returns values, a SUBROUTINE that doesn’t return a value, and one must be the “main program”

  14. Main Program • The main program receives control of the processor when an executable program is loaded for execution. • There can be only one main program in an executable program. • That main program is identified by the fact that it does not have a FUNCTION, SUBROUTINE, or BLOCK DATA statement as its initial statement.

  15. Intrinsic Functions • FORTRAN 77 has many intrinsic functions • Examples • SQRT( ) square root • FLOAT( ),INT ( ) type conversions • COS( ),SIN( ), TAN( ) trig functions

  16. Statement Functions • Statement functions are one line defined functions that is internal to the program unit in which it is defined • Example of a statement function • ROOT(A,B,C) = (-B+SQRT(B**2-4.0*A*C))/(2.0*A)

  17. Subprograms • The main abstraction devices in FORTRAN 77 are the subroutines and functions. • The subroutine definition • SUBROUTINE SWAP (I,J) M = I I = J J = M RETURN END Functions are structurally similar to subroutines.

  18. Control Structures • GOTO statements • IF statements • DO statement • CONTINUE statement • STOP and PAUSE statements • END statement

  19. GOTO Statements • The GOTO statement is used to direct program control to indicated by the statement number specified in the respective GOTO statement • Three types of GOTO statements • Unconditional GOTO 100 • Computed GOTO(1,2,3)I • Assigned GOTO I,(1,2,3)

  20. IF Statements • Contains IF, ELSE IF, ELSE, END IF • Example • IF(Q) THEN A=B C=D ELSE IF (R) THEN E=F G=H ELSE X=Y Z=W END IF

  21. DO Statement • The DO statement is used to establish a controlled loop • Example DO • DO 10 I = 1,10,1

  22. CONTINUE,STOP PAUSE, and END STATEMENT • The CONTINUE statement serves as a point of reference in a program • No operational function is performed • It is frequently used in DO loops to provide a terminal statement • The STOP and PAUSE statements do a similar task • The STOP terminates execution • The PAUSE terminates execution, but leaves the program in a resumable state • The END statement marks the physical end of a program

  23. EVALUATION • Readability • Writability • Reliability • Cost

  24. Readability • FORTRAN 77 is not to hard to read on a small scale, but when many GOTO statements are involved it gets very difficult • Identifiers can only be six characters long

  25. Writability • Depends on what you are using it for. • Is a pretty simply language

  26. Reliability • Is not very reliable • Only static type checking • Lack of exception handling

  27. Cost • Cheap • Lots of free resources/compilers • A fairly easy language to learn

  28. Bibliography • Marshall, A C. A Brief History of FORTRAN 77. 8 Sept. 1997 http://www.liv.ac.uk/HPC/HTMLF90Course/HTMLF90CourseNotesnode29.html • ibiblio.org. A Brief History of FORTRAN. No date http://www.ibiblio.org/pub/languages/fortran/ch1-1.html • American National Standards Institute, Inc. American National Standard Programming Language FORTRAN. April 3, 1978. http://www.fortran.com/F77_std/rjcnf-0.html • Chivers, Ian D. Sleightholme, Jane. Interactive FORTRAN 77: A Hands on Approach 2nd ed. 1984. http://www.kcl.ac.uk/kis/support/cit//fortran/f77book.pdf • William, Waite. FORTRAN 77 Semantic Analysis. No date. http://eli-project.sourceforge.net/fortran_html/Semantics.html#s1 • Bellis, Mary. Inventors of the Modern Computer. No date. http://inventors.about.com/library/weekly/aa072198.htm • Page, Rex. Didday, Rich. Alpert, Elizabeth. FORTRAN 77 for Humans, 3rd ed. 1986 West Publishing Company • Katzan, Harry Jr. FORTRAN 77, Computer Science Series. 1978 Van Nostrand Reinhold Company

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