Replace small values by 0: epsilon2zero

### 4.55.1 Replace small values by 0: epsilon2zero

epsilon2zero takes as argument an expression of x.
epsilon2zero returns the expression where the values of modulus less than epsilon are replaced by zero. The expression is not evaluated.
The epsilon value is defined in the cas configuration (by default epsilon=1e-10).
Input :

epsilon2zero(1e-13+x)

Output (with epsilon=1e-10) :

0+x

Input :

epsilon2zero((1e-13+x)*100000)

Output (with epsilon=1e-10) :

(0+x)*100000

Input :

epsilon2zero(0.001+x)

Output (with epsilon=0.0001) :

0.001+x