Introduction to Programming with Fortran
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Practical Exercise 1 (Compilation and Editing)
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Question 1
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The following program reads in a number and prints its inverse:

    PROGRAM INVERT
        IMPLICIT NONE
        REAL :: Value, Inverse
        PRINT *, "Type in a value to invert"
        READ *, Value
        Inverse = 1.0/Value
        PRINT *, "Value", Value, "  Inverse", Inverse
    END PROGRAM INVERT


1.1 Using an editor, type the above program into a file called something
like `invert.f90'.


1.2 Compile and run the program.  Verify the correctness of the code by
supplying the following test data (each value needs a separate run):

    1.0
    3.0
    -20.0
    1000.0
    1.0e-30


Save a copy of this program in another file (say `invert.safe').


1.3 See what happens when you supply the following data (each value
needs a separate run):

    0.0
    1.0e-38
    1.0e-40
    weeble


1.4 Edit the file, change the occurrence of `Value' to `Vole' in the
`READ' statement, and see what happens when you compile it.


1.5 Restore the file from the safe copy, change the `READ' to `RODE',
and see what happens when you compile it.


1.6 Restore the file from the safe copy, change the first `Value' to
`valUE', and the `Type' to `TYPE'.  Now see what happens when you
compile and run it with the following input:

    1.0