The continued fraction factorization method (**CFRAC**) is a general-purpose factorization algorithm valid for integers. It calculates factors of a given integer number without considering its unique properties. It has a sub-exponential running time. It was first described in 1931 by D. H. Lehmer and R. E. Powers and later in 1975 were developed into a computer algorithm by Michael A. Morrison and John Brillhart.

**Continued Fraction:**

An expression that can be expressed in the form:

(1)

is called a Continued Fraction, where a_{i} and b_{i }are either real or complex values for all *i > = 0*. When all the values of b_{i}‘s_{ }are 1, then it is called a simple continued fraction.

A Simple Continued Fraction can be denoted as:

(2)

where C_{k}= [a_{0; }a_{1}, a_{2}, …, a_{n}] for k<=n is the k-th convergent of the Simple Continued Fraction.

An Infinite Continued Fraction [a_{0}; a_{1}, a_{2}, …, a_{k, }…] is defined as a limit of the convergents C_{k}=[a0; a1, a2, …, an]

**Algorithm:**

This algorithm uses residues produced in the Continued Fraction of (mn)^{1/2} for some m to produce a square number.

This algorithm solves the mathematical equation:

(3)

this equation is solved by calculating the value of m such that m

^{2 }(mod(n)) has the minimum upperbound.

- CFRAC algorithm has a time complexity of:

(4)

**Example 1:**

Input: continued_fraction((10/7)) Output: [1, 2, 3]Explanation:

(5)

**Example 2:**

Input: list(continued_fraction_convergents([0, 2, 1, 2])) Output: [0, 1/2, 1/3, 3/8]Explanation:

(6)

**Example 3:**

Input: continued_fraction_reduce([1, 2, 3, 4, 5]) Output: 225/157Explanation:

(7)

**Implementation:**

**Code: To convert a fraction into Continued Fraction representation**

`#using sympy module` `from` `sympy.ntheory.continued_fraction ` `import` `continued_fraction` `from` `sympy ` `import` `sqrt` `#calling continued_fraction method` `continued_fraction(` `10` `/` `7` `)` |

**Output:**

[1, 2, 3]

**Code 2: To convert a Continued Fraction into fraction.**

`#using sympy module` `from` `sympy.ntheory.continued_fraction ` `import` `continued_fraction_reduce ` ` ` `#calling continued_fraction_reduce method` `continued_fraction_reduce([` `1` `, ` `2` `, ` `3` `, ` `4` `, ` `5` `])` |

**Output:**

225/157

**Code 3: To get a list of convergents from a Continued fraction.**

`# using sympy module` `from` `sympy.core ` `import` `Rational, pi` `from` `sympy ` `import` `S` `from` `sympy.ntheory.continued_fraction ` `import` `continued_fraction_convergents, continued_fraction_iterator ` `# calling continued_fraction_convergents method and ` `# passing it as a parameter to a list` `list` `(continued_fraction_convergents([` `0` `, ` `2` `, ` `1` `, ` `2` `]))` |

**Output:**

[0, 1/2, 1/3, 3/8]

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