A Brief Introduction to Fortran 77 - Polaris

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A declarator can also appear in a dimension statement,Thus:real adimension a(10,10), b(5:15,5)is equivalent to ( b is implicitly declared as real)real a(10,10), b(5:15,5)Note: Dimension declarators for subroutine parameters cancontain variables or can be the special character *.© 1998 David A. Padua12 of 118
ExpressionsExpressions in Fortran can be arithmetic, relational, logical andcharacter.Arithmetic expressions are similar to those in C, except that inFortran there is an exponentiation operator (**) which has thehighest precedence. Thus, the right-hand side expression inthe statementa = 2*b**3-1has the value:2b 3 – 1Implicit type conversion is also similar to C.The division of two integers is an integer. Thus, to test whethera n integer variable is even we can us the condition(n/2)*2.EQ.nThe only character operator is concatenation (//):© 1998 David A. Padua13 of 118
Page 1 and 2: A Brief Introduction to Fortran 771
Page 3 and 4: InterpretersAn interpreter is a pro
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: A scalar variable does not have to
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$ompc$
Page 53 and 54: The syntax of the pdo directive is
Page 55 and 56: 6.6 The PARALLEL DO directiveAn alt
Page 57 and 58: And the routine pdo_2 can be rewrit
Page 59 and 60: 6.7 The PSECTIONS directiveAn alter
Page 61 and 62: end© 1998 David A. Padua61 of 118
Page 63 and 64:
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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