Thanks for the help.

Line 439: double round (double __x) __ATTR_CONST__;

THE WHOLE MATH.H BELOW:

[code]/* Copyright (c) 2002,2007 Michael Stumpf

Portions of documentation Copyright (c) 1990 - 1994

The Regents of the University of California.

All rights reserved.

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright

notice, this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright

notice, this list of conditions and the following disclaimer in

the documentation and/or other materials provided with the

distribution.

* Neither the name of the copyright holders nor the names of

contributors may be used to endorse or promote products derived

from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE. */

/* $Id: math.h,v 1.21.2.2 2008/04/10 13:39:16 arcanum Exp $ */

/*

math.h - mathematical functions

Author : Michael Stumpf

Michael.Stumpf@t-online.de

__ATTR_CONST__ added by marekm@linux.org.pl for functions

that "do not examine any values except their arguments, and have

no effects except the return value", for better optimization by gcc.

*/

#ifndef __MATH_H

#define __MATH_H

/** \file */

/** \defgroup avr_math <math.h>: Mathematics

\code #include <math.h> \endcode

This header file declares basic mathematics constants and

functions.

\par Notes:

- In order to access the functions delcared herein, it is usually

also required to additionally link against the library \c libm.a.

See also the related \ref faq_libm "FAQ entry".

- Math functions do not raise exceptions and do not change the

\c errno variable. Therefore the majority of them are declared

with const attribute, for better optimization by GCC. */

/**

\ingroup avr_math

The constant \c pi. */

#define M_PI 3.141592653589793238462643

/**

\ingroup avr_math

The square root of 2. */

#define M_SQRT2 1.4142135623730950488016887

/**

\ingroup avr_math

NAN constant. */

#define NAN __builtin_nan("")

/**

\ingroup avr_math

INFINITY constant. */

#define INFINITY __builtin_inf()

#ifndef __ATTR_CONST__

# define __ATTR_CONST__ __attribute__((__const__))

#endif

#ifdef __cplusplus

extern "C" {

#endif

/**

\ingroup avr_math

The cos() function returns the cosine of \a __x, measured in radians.

*/

extern double cos(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The fabs() function computes the absolute value of a floating-point

number \a __x.

*/

extern double fabs(double __x) __ATTR_CONST__;

#if 0

/* fabs seems to be built in already */

static inline double fabs( double __x )

{ double __res;

__asm__ __volatile__ ("andi %D0,0x7F \n\t"

: "=d" (__res) : "0" (__x) );

return __res;

}

#endif

/**

\ingroup avr_math

The function fmod() returns the floating-point remainder of <em>__x /

__y</em>.

*/

extern double fmod(double __x, double __y) __ATTR_CONST__;

/**

\ingroup avr_math

The modf() function breaks the argument \a __x into integral and

fractional parts, each of which has the same sign as the argument.

It stores the integral part as a double in the object pointed to by

\a __iptr.

The modf() function returns the signed fractional part of \a __x.

\note

This implementation skips writing by zero pointer.

*/

extern double modf(double __x, double *__iptr);

/**

\ingroup avr_math

The sin() function returns the sine of \a __x, measured in radians.

*/

extern double sin(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The sqrt() function returns the non-negative square root of \a __x.

*/

extern double sqrt(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The tan() function returns the tangent of \a __x, measured in

radians.

*/

extern double tan(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The floor() function returns the largest integral value less than or

equal to \a __x, expressed as a floating-point number.

*/

extern double floor(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The ceil() function returns the smallest integral value greater than

or equal to \a __x, expressed as a floating-point number.

*/

extern double ceil(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The frexp() function breaks a floating-point number into a normalized

fraction and an integral power of 2. It stores the integer in the \c

int object pointed to by \a __pexp.

If \a __x is a normal float point number, the frexp() function

returns the value \c v, such that \c v has a magnitude in the

interval [1/2, 1) or zero, and \a __x equals \c v times 2 raised to

the power \a __pexp. If \a __x is zero, both parts of the result are

zero. If \a __x is not a finite number, the frexp() returns \a __x as

is and stores 0 by \a __pexp.

\note This implementation permits a zero pointer as a directive to

skip a storing the exponent.

*/

extern double frexp(double __x, int *__pexp);

/**

\ingroup avr_math

The ldexp() function multiplies a floating-point number by an integral

power of 2.

The ldexp() function returns the value of \a __x times 2 raised to

the power \a __exp.

*/

extern double ldexp(double __x, int __exp) __ATTR_CONST__;

/**

\ingroup avr_math

The exp() function returns the exponential value of \a __x.

*/

extern double exp(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The cosh() function returns the hyperbolic cosine of \a __x.

*/

extern double cosh(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The sinh() function returns the hyperbolic sine of \a __x.

*/

extern double sinh(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The tanh() function returns the hyperbolic tangent of \a __x.

*/

extern double tanh(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The acos() function computes the principal value of the arc cosine of

\a __x. The returned value is in the range [0, pi] radians. A domain

error occurs for arguments not in the range [-1, +1].

*/

extern double acos(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The asin() function computes the principal value of the arc sine of

\a __x. The returned value is in the range [-pi/2, pi/2] radians. A

domain error occurs for arguments not in the range [-1, +1].

*/

extern double asin(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The atan() function computes the principal value of the arc tangent

of \a __x. The returned value is in the range [-pi/2, pi/2] radians.

*/

extern double atan(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The atan2() function computes the principal value of the arc tangent

of <em>__y / __x</em>, using the signs of both arguments to determine

the quadrant of the return value. The returned value is in the range

[-pi, +pi] radians.

*/

extern double atan2(double __y, double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The log() function returns the natural logarithm of argument \a __x.

*/

extern double log(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The log10() function returns the logarithm of argument \a __x to base

10.

*/

extern double log10(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The function pow() returns the value of \a __x to the exponent \a __y.

*/

extern double pow(double __x, double __y) __ATTR_CONST__;

/**

\ingroup avr_math

The function isnan() returns 1 if the argument \a __x represents a

"not-a-number" (NaN) object, otherwise 0.

*/

extern int isnan(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The function isinf() returns 1 if the argument \a __x is positive

infinity, -1 if \a __x is negative infinity, and 0 otherwise.

*/

extern int isinf(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The function square() returns <em>__x * __x</em>.

\note

This function does not belong to the C standard definition.

*/

extern double square(double __x) __ATTR_CONST__;

/**

\ingroup avr_math

The copysign() function returns \a __x but with the sign of \a __y.

They work even if \a __x or \a __y are NaN or zero.

*/

__ATTR_CONST__ stat