Numerical Inquiry and Manipulation Functions

 

Fortran 90 introduces several intrinsic functions to inquire about machine dependent characteristics of an integer or real. For example, the inquiry function, huge, can be used to find the largest machine representable number for an integer or real value. The integer model used by these inquiry functions is

 where

      		 i  is the integer value

      		 s 		 is the sign (+1 or -1)

      		 r 		 is the radix (r > 1)

      		 q 		 is the number of digits (q > 0)

      		    		 is the kth digit,   .

The floating-point model used by the inquiry functions is

 where

      		 x  is the real value

      		 s 		 is the sign (+1 or -1)

      		 b 		 is the base (b > 1)

      		 e 		 is the exponent

      		 p 		 is the number of mantissa
		 digits (p > 1)

      		    		 is the kth digit,   ,
                    .

Table 1 lists intrinsic functions that inquire about the numerical environment. Table 2 lists intrinsic functions that manipulate the numerical characteristics of variables in the real model. An important feature of all of these intrinsic functions is that they are generic and may be used to obtain information about any kind of integer or real supported by the Fortran 90 implementation.

  
Table 1: Numeric Inquiry Functions

  
Table 2: Numeric Manipulation Functions