### 2.8.1 Transform a floating point number into a rational : `exact
float2rational`

`float2rational` or `exact` takes as argument a floating point number `d` and returns a rational number `q` approaching `d` such that `abs(d-q)<epsilon`. `epsilon` is defined in the `cas` configuration (`Cfg` menu) or with the `cas_setup` command.
Input :

`float2rational(0.3670520231)`

Output when `epsilon=1e-10`:

`127/346`

Input :

`evalf(363/28)`

Output :

`12.9642857143`

Input :

`float2rational(12.9642857143)`

Output :

`363/28`

If two representations are mixed, for example :

`1/2+0.7`

the rational is converted to a float, output :

`1.2`

Input :

`1/2+float2rational(0.7)`

Output :

`6/5`