_filteq(s1, s2, s3, s4, i4, s5, i5, dwin)
{
        local form;

        if (i5)   /* initial x conditions */
        {
                if (i4)
                {
                        form = sprintf("Filteq(%s, %s, %s, %s, %s)", s1, s2, s3, s4, s5);
                }
                else
                {
                        form = sprintf("Filteq(%s, %s, %s, {0}, %s)", s1, s2, s3, s5);
                }
        }
        else if (i4)   /* just y initial conditions */
        {
                form = sprintf("Filteq(%s, %s, %s, %s)", s1, s2, s3, s4);
        }
        else
        {
                form = sprintf("Filteq(%s, %s, %s)", s1, s2, s3);
        }

        eval(sprintf("setwf(%s, '%s')", dwin, form));
}