real

OpenTuring

realthe real number type

Syntax   real

Description   The real number type is used for numbers that have fractional parts, for example, 3.14159. Real numbers can be combined by various operators such as addition (+) and multiplication (*). Real numbers can also be combined with integers (whole numbers, such as 23, 0 and -9), in which case the result is generally a real number. An integer can always be assigned to a real variable, with implicit conversion to real.

Example  

        var weight, x : real
        var x : real := 9.83
        var tax := 0.7      % The type is implicitly real because
                        % 0.7 is a real number

Details   See also explicitRealConstant. The int type is used instead of real, when values are whole numbers. See int for details.

Real numbers can be converted to integers using ceil (ceiling), floor, or round. Real numbers can be converted to strings using erealstr, frealstr, and realstr. These conversion functions correspond exactly to the formatting used for the put statement with real numbers. Strings can be converted to real numbers using strreal. See descriptions of these conversion functions.

The predefined functions for real numbers include min, max, sqrt, sin, cons, arctan, sind, cosd, arcand, ln and exp. See the descriptions of these functions.

Pseudo-random sequences of real numbers can be generated using rand. See the description of this procedure.

The Turing Report gives a formal definition (not repeated here) of implemented real numbers in terms of their required accuracy relative to infinitely accurate (mathematical) real numbers.

Turing implements real numbers using 8 byte floating point representation. This provides 14 to 16 decimal digits of precision and an exponent range of at least -38 .. 38. The PC and Macintosh versions of Turing have 16 decimal digits of accuracy because they use IEEE standard floating point representation.

See also   realn.