Getting Started |

**while **

The `while`

loop repeats a group of statements an indefinite number of times under control of a logical condition. A matching `end`

delineates the statements.

Here is a complete program, illustrating `while`

, `if`

, `else`

, and `end`

, that uses interval bisection to find a zero of a polynomial.

a = 0; fa = -Inf; b = 3; fb = Inf; while b-a > eps*b x = (a+b)/2; fx = x^3-2*x-5; if sign(fx) == sign(fa) a = x; fa = fx; else b = x; fb = fx; end end x

The result is a root of the polynomial *x*^{3 }- 2*x* - 5, namely

The cautions involving matrix comparisons that are discussed in the section on the `if`

statement also apply to the `while`

statement.

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