if (xc2 < -D_EPSILON || fabs(yc2) > F_EPSILON) {
sys_error (ERR_SEVERE, "Internal error in clip_circle\n x1=%6.2f, y1=%6.2f, x2=%6.2f, y2=%6.2f, xc2=%6.2f, yc2=%6.2f, theta=%6.2f", x1, y1, x2, y2, xc2, yc2, theta);
if (xc2 < -D_EPSILON || fabs(yc2) > F_EPSILON) {
sys_error (ERR_SEVERE, "Internal error in clip_circle\n x1=%6.2f, y1=%6.2f, x2=%6.2f, y2=%6.2f, xc2=%6.2f, yc2=%6.2f, theta=%6.2f", x1, y1, x2, y2, xc2, yc2, theta);