خروجی حقیقی

REAL Output: The E Descriptor

The Ew.d and Ew.dEe descriptors are for REAL output. The printed numbers will be in an exponential form. The general form of these descriptors are discussed below. There are two more forms, ESw.d and ENw.d, which will be discussed at the bottom of this page.

 

rEw.d     and     rEw.dEe

The meaning of r, w, d and e are:

E is for REAL numbers in exponential forms.

w is the width of field, which indicates that a real number should be printed with w positions.

To print a number in an exponential form, it is first converted to a normalized form s0.xxx...xxx×10^sxx, where s is the sign of the number and the exponent and x is a digit. For example, 12.345, -12.345, 0.00123 and -0.00123 are converted to 0.12345×10², -0.12345×10², 0.123×10^-2 and -0.123×10^-2.

The Ew.d descriptor generates real numbers in the following form

Examples

In the following table, the WRITE statements use different E edit descriptors to print the value of 3.1415926. The WRITE statements are shown in the left and their corresponding output, all using 12 positions, are shown in the right.

 

 

The first example uses E12.5 to print 3.1415926. This number is first converted to 0.31415926×10¹. Therefore, the normalized number is 0.31415926 and the exponent is 1. The exponent part is printed as E+01. Since we have only 5 positions for printing 0.31415926 which has 8 digits, the sixth one will be rounded to the fifth and the result is 0.31416.

The second example uses E12.3E4 to print the same number. This E descriptor indicates that four positions are for the exponent and, as a result, the printed exponent part is E+0001.

The last example is obvious. However, if the number is changed to -3.1415926, the result will be 12 asterisks, since there is no position for the sign of the number