A Brief Introduction to Fortran 77 - Polaris

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Fortran is not a flower, but a weed. It is hardy, occasionallyblooms, and grows in every computer. (A. Perlis)• In 1954 a project was begun under the leadership of JohnBackus at IBM to develop an "automatic programming"system that would convert programs written in amathematical notation to machine instructions for the IBM704 computer.• Many were skeptical that the project would be successful. Itwas necessary for the program produced by the compiler tobe almost as efficient as that produced by a good assemblylanguage programmer.• First compiler in 1957. Quite successful.• Several ANSI standards: 1966 (Fortran 66), 1978 (Fortran77), 1990 (Fortran 90), 1995 (Fortran 95).2 of 118
InterpretersAn interpreter is a program that performs the operationsimplied by the source program. For an assignment statement,for example, an interpreter might build a tree like:=position +initial *rate 60an then carry out the operations at the nodes as it walks thetree.Very high-evel languages, like APL and MATLAB, are usuallyinterpreted because there are many things about the data,such as size and shape of arrays, that cannot be dedueced atcompile time.© 1998 David A. Padua3 of 118
Page 1: A Brief Introduction to Fortran 771
Page 5 and 6: Source formTraditionally, Fortran s
Page 7 and 8: Lower case letters are considered e
Page 9 and 10: The form of a character constant is
Page 11 and 12: A scalar variable does not have to
Page 13 and 14: ExpressionsExpressions in Fortran c
Page 15 and 16: The logical operators are:.NOT. Log
Page 17 and 18: 3. DO statement. Iterative statemen
Page 19 and 20: Program UnitsA Fortran program alwa
Page 21 and 22: Notice that the variable y in the l
Page 23 and 24: Each read starts on the next record
Page 25 and 26: function rtflsp(func,x1,x2,xacc)par
Page 27 and 28: A Brief Introduction to Fortran 90
Page 29 and 30: IMPLICIT none29 of 118
Page 31 and 32: Array Shapes and SizesThe shape of
Page 33 and 34: Fortran 90 Intrinsic Proceduresaint
Page 35 and 36: Finer control on when an array is c
Page 37 and 38: Procedure InterfacesWhen a procedur
Page 39 and 40: Expressions in Fortran 90 may conta
Page 41 and 42: In the following compound statement
Page 43 and 44: 6.1 IntroductionOpenMP is a collect
Page 45 and 46: All variables are assumed to be sha
Page 47 and 48: Notice that the first statement can
Page 49 and 50: 6.4 The PSINGLE directiveFinally, s
Page 51 and 52: A better example of psingle:c$ompc$
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The syntax of the pdo directive is
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6.6 The PARALLEL DO directiveAn alt
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And the routine pdo_2 can be rewrit
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6.7 The PSECTIONS directiveAn alter
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end© 1998 David A. Padua61 of 118
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Chapter 7. Parallel Loops in OpenMP
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Chapter 6. OpenMP65 of 118
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Another example of a race is:c$omp
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Another example is:c$ompparallel do
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7.2 Race-free parallel loopsNext, w
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7.3 PrivatizationSometimes the tran
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Sometimes it is necessary to privat
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One way to solve this problem is to
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Variables in lastprivate are privat
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print *,a(1),a(2)endprints1.000000
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To account for this, a and b should
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Most induction variables are quite
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Here, again, only the induction var
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The way to remove the races produce
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We can now proceed as above to obta
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However, there is a way to improve
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Notice that now no races exist beca
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7.6 Execution time of a parallel do
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following time lines:abcdeDabcdeDDa
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7.6 Critical Regions and Reductions
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Here, we use the critical directive
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The assumption is that it does not
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© 1998 David A. Padua108 of 118
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A Brief Introduction to Fortran 77 - Polaris

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