6.6.1  Defining intervals

An interval is a range of real numbers, whose end points will be floats with at least 15 significant digits. The i command creates intervals, with the arguments in square brackets.

• i takes two arguments: a and b, two real numbers.
• i[a,b] returns the interval between a and b.

  If a > b, then i[a,b] returns i[evalf(b,15)-epsilon,evalf(a,15)+epsilon] (see Section 2.5.7, item 2.5.7).

Intervals can also be created by following a decimal number with a question mark. If the decimal number contains n digits, the interval will be centered at a and have width 2· 10⁻ⁿ.

Examples