C4LIB
Elementary functions for single precision complex variables

C4LIB is a C library which defines single precision complex numbers and the operations necessary to do arithmetic on them.

The original C specification did not include support for complex numbers. While later versions of the ANSI standard did include specifications for complex number support, the actual implementation of this standard seems to be irregular and inconsistent. Although C++ includes solid support for complex numbers, there may be situations where a small amount of complex arithmetic is needed in a C programming context.

To use the structures and functions of this library, it is necessary that the user's source code invoke the include file:

        # include "c4lib.h"
      

This package defines a single precision complex number as a C struct whose components are floats:

        struct c4_complex
        {
          float real;
          float imag;
        };
      

To declare a variable c you could use a statement like:

        struct c4_complex c;
      

The declaration can include an initialization:

        struct c4_complex c = { 1.0, 2.0 };
      

The value of a variable c declared as struct c4_complex may be examined or changed by accessing the components of the struct. Thus, the initialization above could be carried out at run time by the commands:

        c.real = 1.0;
        c.imag = 2.0;
      

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Programs:

BLAS1_C is a C library which contains basic linear algebra routines for vector-vector operations, using single precision complex arithmetic.

C8LIB, a C library which implements certain elementary functions for double precision complex variables;

C4LIB is available in a C version and a FORTRAN77 version and a FORTRAN90 version.

MY_COMPLEX, a C++ class for complex numbers;

Source Code:

• c4lib.c, the source code;
• c4lib.h, the include file.
• c4lib.csh, commands to compile the source code;

Examples and Tests:

• c4lib_prb.c, the calling program;
• c4lib_prb.csh, commands to compile, link and run the calling program;
• c4lib_prb_output.txt, the output file.

List of Routines:

• C4_ABS returns the absolute value of a C4.
• C4_ACOS evaluates the inverse cosine of a C4.
• C4_ACOSH evaluates the inverse hyperbolic cosine of a C4.
• C4_ADD adds two C4's.
• C4_ARG returns the argument of a C4.
• C4_ASIN evaluates the inverse sine of a C4.
• C4_ASINH evaluates the inverse hyperbolic sine of a C4.
• C4_ATAN evaluates the inverse tangent of a C4.
• C4_ATANH evaluates the inverse hyperbolic tangent of a C4.
• C4_CONJ conjugates a C4.
• C4_COPY copies a C4.
• C4_COS evaluates the cosine of a C4.
• C4_COSH evaluates the hyperbolic cosine of a C4.
• C4_CUBE_ROOT computes the principal cube root of a C4.
• C4_DIV divides two C4's.
• C4_DIV_R4 divides a C4 by an R4.
• C4_EXP exponentiates a C4.
• C4_I returns the value of I as a C4
• C4_IMAG returns the imaginary part of a C4.
• C4_INV inverts a C4.
• C4_LOG evaluates the logarithm of a C4.
• C4_MAG returns the magnitude of a C4.
• C4_MUL multiplies two C4's.
• C4_NEG negates a C4.
• C4_NORMAL_01 returns a unit pseudonormal C4.
• C4_ONE returns the value of 1 as a C4
• C4_REAL returns the real part of a C4.
• C4_SIN evaluates the sine of a C4.
• C4_SINH evaluates the hyperbolic sine of a C4.
• C4_SQRT computes a square root of a C4.
• C4_SUB subtracts two C4's.
• C4_SWAP swaps two C4's.
• C4_TAN evaluates the tangent of a C4.
• C4_TANH evaluates the hyperbolic tangent of a C4.
• C4_TO_CARTESIAN converts a C4 to Cartesian form.
• C4_TO_POLAR converts a C4 to polar form.
• C4_UNIFORM_01 returns a unit pseudorandom C4.
• C4_ZERO returns the value of 0 as a C4
• CARTESIAN_TO_C4 converts a Cartesian form to a C4.
• POLAR_TO_C4 converts a polar form to a C4.
• R4_UNIFORM_01 returns a unit pseudorandom R4.
• SORT_HEAP_EXTERNAL externally sorts a list of items into ascending order.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C source codes.