### 2.54.7 Rational approximation : `float2rational exact`

`float2rational` (or `exact`) takes as argument an expression.
`float2rational` returns a rational approximation of all the floating point numbers r contained in this expression, such that |r−`float2rational`(r)|<є, where є is defined by `epsilon` in the `cas` configuration (`Cfg` menu, or `cas_setup` command).
Input :

`float2rational(1.5)`

Output :

`3/2`

Input :

`float2rational(1.414)`

Output :

`707/500`

Input :

`float2rational(0.156381102937*2)`

Output :

`5144/16447`

Input :

`float2rational(1.41421356237)`

Output :

`114243/80782`

Input :

`float2rational(1.41421356237```^```2)`

Output :

`2`