A Brief Introduction to Fortran 77 - Polaris

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Fortran includes a number of pre-defined intrinsic functionssuch as sin, cos, max, sign, etc. These are described inany Fortran manual.Statement functions are declared at the beginning of theprogram. The declaration has the form:fun ( d, d, ...) = ewhere the d’s are dummy arguments and e is an expressionthat may contain constants, dummy arguments, programvariables and references to any type of function.The type of the value returned by the statement functiondepends on the type associated with the function name. Thetype is assigned using either type declaration statements or, ifthe function name is not declared, the implicit rules describedabove for variables. An example of a statement function is:real mpyadd, b(100)...mpyadd(x,y,z) = x*y + z + 2 + sin(x)...y = mpyadd(a,b(5),1.0)© 1998 David A. Padua20 of 118
Notice that the variable y in the last assignment statement isdifferent from the dummy argument in the statement function.In fact, dummy arguments in a statement function have ascope of that statement.External functions can be compiled separately from the mainprogram. They may include several executable statements.Their overall form is: FUNCTION fun (d ,d, ...)ENDDeclarations and executable statementsThe name of the function (fun) must appear as a variablewithin the subprogram. The variable must be defined on everyexecution of the function, and its value at the end of thesubprogram is the value returned by the function.The type of the (value returned by) function is determinedeither using the implicit rules or by the specified in thefunction header.© 1998 David A. Padua21 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 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: Program UnitsA Fortran program alwa
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
Page 65 and 66: Chapter 6. OpenMP65 of 118
Page 67 and 68: Another example of a race is:c$omp
Page 69 and 70: Another example is:c$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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