### 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).