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/* -*- c++ -*- */
/*
* Copyright 2003,2005 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* mathematical odds and ends.
*/
#ifndef _GR_MATH_H_
#define _GR_MATH_H_
long gr_gcd (long m, long n);
// returns a non-zero value if value is "not-a-number" (NaN), and 0 otherwise
int gr_isnan (double value);
// returns a non-zero value if the value of x has its sign bit set.
//
// This is not the same as `x < 0.0', because IEEE 754 floating point
// allows zero to be signed. The comparison `-0.0 < 0.0' is false, but
// `gr_signbit (-0.0)' will return a nonzero value.
int gr_signbit (double x);
/*!
* \brief Fast arc tangent using table lookup and linear interpolation
*
* \param y component of input vector
* \param x component of input vector
* \returns float angle angle of vector (x, y) in radians
*
* This function calculates the angle of the vector (x,y) based on a
* table lookup and linear interpolation. The table uses a 256 point
* table covering -45 to +45 degrees and uses symetry to determine the
* final angle value in the range of -180 to 180 degrees. Note that
* this function uses the small angle approximation for values close
* to zero. This routine calculates the arc tangent with an average
* error of +/- 0.045 degrees.
*/
float gr_fast_atan2f(float y, float x);
#endif /* _GR_MATH_H_ */
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