xfree86 man page for complex

complex.h(3HEAD)						      Headers							  complex.h(3HEAD)

NAME
       complex.h, complex - complex arithmetic

SYNOPSIS
       #include <complex.h>

DESCRIPTION
       The <complex.h> header defines the following macros:

       complex	       Expands to _Complex.

       _Complex_I      Expands	to  a  constant expression of type const float _Complex, with the value of the imaginary unit (that is, a number i
		       such that i2-1).

       imaginary       Expands to _Imaginary.

       _Imaginary_I    Expands to a constant expression of type const float _Imaginary with the value of the imaginary unit.

       I	       Expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is  not defined, I expands to _Complex_I.

       An application can undefine and then, if appropriate, redefine the complex, imaginary, and I macros.

USAGE
       Values are interpreted as radians, not degrees.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       cabs(3M), cacos(3M), cacosh(3M),  carg(3M),  casin(3M),	casinh(3M),  catan(3M),  catanh(3M),  ccos(3M),  ccosh(3M),  cexp(3M),	cimag(3M),
       clog(3M), conj(3M), cpow(3M), cproj(3M), creal(3M), csin(3M), csinh(3M), csqrt(3M), ctan(3M), ctanh(3M), attributes(5), standards(5)

NOTES
       The  choice of I instead of i for the imaginary unit concedes to the widespread use of the identifier i for other purposes. The application
       can use a different identifier, say j, for the imaginary unit by following the inclusion of the <complex.h> header with:

       #undef I
       #define j _Imaginary_I

       An I suffix to designate imaginary constants is not required, as multiplication by I provides a sufficiently convenient and more  generally
       useful notation for imaginary terms. The corresponding real type for the imaginary unit is float, so that use of I for algorithmic or nota-
       tional convenience does not result in widening types.

       On systems with imaginary types, the application has the ability to control whether use of the macro I introduces  an  imaginary  type,	by
       explicitly defining I to be _Imaginary_I or _Complex_I.

       Disallowing imaginary types is useful for some applications intended to run on implementations without support for such types.

       The macro _Imaginary_I provides a test for whether imaginary types are supported. The cis() function (cos(x) + I*sin(x)) was considered but
       rejected because its implementation is easy and straightforward, even though some implementations could compute sine and cosine more  effi-
       ciently in tandem.

SunOS 5.10							    17 Dec 2003 						  complex.h(3HEAD)