C-REAL

C-REAL refers to a proposed data type and associated implementation in the C programming language, intended to represent complex numbers with real and imaginary parts both represented as floating-point numbers. While not a standard data type defined in the original ANSI C specification (C89) or later C99 and C11 standards, some compilers and libraries offer extensions or implementations that effectively function as a C-REAL type.

Essentially, a C-REAL type would be a structure containing two floating-point members, typically named 'real' and 'imag', representing the real and imaginary components of the complex number respectively. Operations on C-REAL variables, such as addition, subtraction, multiplication, division, and conjugation, would require custom functions or operator overloading (in C++ implementations) to correctly perform the complex number arithmetic.

The lack of a built-in C-REAL type in standard C necessitated the use of alternative methods for complex number manipulation. One common approach involved defining a structure representing a complex number and creating separate functions to perform operations on these structures. Another option was to utilize external libraries, such as the GNU Scientific Library (GSL), which provide comprehensive support for complex number arithmetic, including pre-defined complex number types and associated functions. The C99 standard eventually introduced the complex data type (and related keywords _Complex, I) providing standardized complex number support, which largely superseded the need for custom C-REAL implementations.