ALTRAN (ALgebraic TRANslator) is a FORTRAN extension providing rational algebra[definition needed], developed by W.S. Brown, at Bell Labs around 1968. ALTRAN, a FORTRAN version of ALPAK. "can be thought of as a variant of FORTRAN with the addition of an extra declaration, the 'algebraic' type declaration." ALPAK, written in 1964, originally consisted of a set of subroutines for FORTRAN written in assembly language. These subroutines were themselves rewritten in FORTRAN for ALTRAN.
Although ALTRAN is written in ANSI FORTRAN, nevertheless there exist differences in FORTRAN implementations. ALTRAN handles machine dependencies through the use of a macro preprocessor called M. In 1979, ALTRAN was ported to the Control Data Corporation 6600 and Cyber 176 computers at the Air Force Weapons Laboratory. They found that "ALTRAN is about 15 times faster than FORMAC…, and it is at least 12 times faster than REDUCE."
ALTRAN should not be confused with the ALGOL to FORTRAN Translator, called Altran, that "converts Extended Algol programs into Fortran IV."
PROCEDURE MAIN # SIMPLE EXAMPLE OF USE OF FTNOUT LONG ALGEBRAIC (X:10,Y:10) F ALTRAN FTNOUT OPTS(201,72) # FTNOUT REQUIRES A LINE LENGTH OF 72 F = EXPAND( (X+2*Y+1000000)**3 ) WRITE F # PRINT F WRITE (25) " FUNCTION F(X,Y)" "C EXAMPLE PROG WRITTEN WITH FTNOUT." , F , " RETURN"™, " END" # WE HAVE WRITTEN A SIMPLE PROGRAM ON UNIT 25, NOW WE INVOKE FTNOUT TO # THIS ALTRAN OUTPUT TO LEGAL FORTRAN. FTNOUT END
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- W.S. Brown, ALTRAN User's Manual (2nd ed.), Bell Laboratories, Murray Hill, N.J., 1972.
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