Function generaterotation

src/rotations.cpp:306–347

The subroutine generates the elementary rotation, so that: [ CS SN ] . [ F ] = [ R ] [ -SN CS ] [ G ] [ 0 ] CS**2 + SN**2 = 1 *************************************************************************/

CS**2 + SN**2 = 1
*************************************************************************/
void generaterotation(double f, double g, double& cs, double& sn, double& r)
{
    double f1;
    double g1;

    if( ap::fp_eq(g,0) )
    {
        cs = 1;
        sn = 0;
        r = f;
    }
    else
    {
        if( ap::fp_eq(f,0) )
        {
            cs = 0;
            sn = 1;
            r = g;
        }
        else
        {
            f1 = f;
            g1 = g;
            if( ap::fp_greater(fabs(f1),fabs(g1)) )
            {
                r = fabs(f1)*sqrt(1+ap::sqr(g1/f1));
            }
            else
            {
                r = fabs(g1)*sqrt(1+ap::sqr(f1/g1));
            }
            cs = f1/r;
            sn = g1/r;
            if( ap::fp_greater(fabs(f),fabs(g))&&ap::fp_less(cs,0) )
            {
                cs = -cs;
                sn = -sn;
                r = -r;
            }
        }
    }
}