Presented by: Destry Diefenbach FORTRAN 77 Presented by: Destry Diefenbach

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)

“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

History of FORTRAN John Backus 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

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

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

FORTRAN II - IV FORTRAN II FORTRAN III FORTRAN IV 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

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

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

Real Data Types Represent decimal numbers It uses scientific notation

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

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

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”

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.

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

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)

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.

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

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)

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

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

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

EVALUATION Readability Writability Reliability Cost

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

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

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

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

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