sign.h

// Description: Sign function
// Documentation: math_functions.txt

#ifndef PASTELSYS_SIGN_H
#define PASTELSYS_SIGN_H

#include "pastel/sys/real/real_concept.h"

namespace Pastel
{

    //! Signum function.
    /*!
   returns:
   -1, if negative,
    0, if zero (or NaN), or
   +1, if positive.
   */
    template <typename Real>
    integer sign(const Real& that)
    {
        // x>0  x<0   Result
        //  no   no   0 (could also be NaN)
        //  no  yes   -1
        // yes   no   +1
        // yes  yes   Impossible.

        return (integer)positive(that) - (integer)negative(that);
    }

}

#endif