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Formatted Output

The table of values would have a better appearance if the decimal points were properly aligned and if there were only two digits after them. The last figure in the table is actually less than a thirtieth of a penny, which is effectively zero to within the accuracy of the machine. A better layout can be produced easily enough by using an explicit format specification instead of the list-directed output used up to now. To do this, the last WRITE statement in the program should be replaced with one like this:
WRITE(UNIT=*, FMT='(1X,I9,F11.2)') IYEAR, AMOUNT
The amended program will then produce a neater tabulation:

 
Enter amount, % rate, years 
2000, 9.5, 5 
Annual repayments are    520.8728     
End of Year  Balance 
        1    1669.13 
        2    1306.82 
        3     910.10 
        4     475.68 
        5        .00
The format specification has to be enclosed in parentheses and, as it is actually a character constant, in a pair of apostrophes as well. The first item in the format list, 1X, is needed to cope with the carriage-control convention: it provides an additional blank at the start of each line which is later removed by the Fortran system. There is no logical explanation for this: it is there for compatibility with very early Fortran system. The remaining items specify the layout of each number: I10 specifies that the first number, an integer, should be occupy a field 10 columns wide; similarly F11.2 puts the second number, a real (floating-point) value, into a field 11 characters wide with exactly 2 digits after the decimal point. Numbers are always right-justified in each field. The field widths in this example have been chosen so that the columns of figures line up satisfactorily with the headings.


next up previous contents index
Next: Functions Up: Basic Fortran Concepts Previous: DO Loops
Helen Rowlands
8/27/1998