.. _cmath:

Mathematical Functions
======================

The math library has several functions to do mathematical
calculations. Except for ``pow()``, each of these programs takes a
single double variable. The following sample of math functions
all return a double.

    ``sqrt(x)``
    :math:`\sqrt{x}`

    ``pow(x,y)``
    :math:`x^y`

    ``exp(x)``
    :math:`e^x`

    ``fabs(x)``
    :math:`|x|`

    ``log(x)``
    :math:`\ln(x)`

    ``log10(x)``
    :math:`\log(x)`

    ``sin(x)``, ``cos(x)``, ``tan(x)``
    Trig functions, x is in radians.

The following file lists more math functions and definitions.
:download:`math_h.txt`

Additional documentation may be found by searching the Internet or a variety of
other sources of documentation.

.. note::

   To use the math functions On Unix platforms, in addition to including the
   ``math.h`` header file in the program it is necessary and to link in the
   math library with the ``-lm`` option to the compiler.

   ::

        #include <stdio.h>
        #include <math.h>
        
        int main(void)
        {
           printf("%6.3lf\t %6.3lf\t %6.3lf\n", 
                       exp(1.0), log(2.72), log10(100.0));
           return 0;
        }
        
        285 hudson:~> gcc -lm test.c
        286 hudson:~> ./a.out 
         2.718     1.001    2.000