code: public static BigFloat acos(BigFloat x) {
  		return x.isNaN() || (!isRangeAbs1(x)) ? NaN :
  				x.context.valueOf(BigDecimalMath.acos(x.value, x.context.mathContext));
  	}
docs: Returns the {@link BigFloat} that is <code>acos(x)</code>.
  
  @param x the value
  
  @return the resulting {@link BigFloat}
  
  @see BigDecimalMath#acos(BigDecimal, MathContext)