Collect logarithms : lncollect

### 2.23.5 Collect logarithms : `lncollect`

`lncollect` takes as argument an expression with logarithms.
`lncollect` collects the logarithms (rewrites sum of ln as ln of products). It may be a good idea to factor the expression with `factor` before collecting by `lncollect`).
Input :

`lncollect(ln(x+1)+ln(x-1))`

Output :

`log((x+1)*(x-1))`

Input :

`lncollect(exp(ln(x+1)+ln(x-1)))`

Output :

`(x+1)*(x-1)`

Warning!!! For `Xcas`, `log=ln` (use `log10` for 10-base logarithm).