Where x is an ArbReal value and other values are ArbFloats.

parts

• midpoint(x), radius(x)
• lowerbound(x), upperbound(x)
• upperbound_abs(x), lowerbound_abs(x)

construction

• setball(midpoint, radius)
• setinterval(lobound, hibound)

retrieval

• midpoint, radius = ball(x)
• lobound, hibound = interval(x)