NAME
    IEEEDPTan -- compute the tangent of a floating point number
SYNOPSIS
      x   = IEEEDPTan(  y  );
    d0/d1             d0/d1
    double  x,y;
FUNCTION
    Compute tangent of y in IEEE double precision
INPUTS
    y - IEEE double precision floating point value
RESULT
    x - IEEE double precision floating point value
BUGS
SEE ALSO
    ieeedpatan(), ieeedpsin(), ieeedpcos()