10.3.5 Collecting logarithms
The lncollect
command collects the logarithm in an expression; namely, it rewrites
sums of logarithms as the logarithm of a product.
-
lncollect takes
expr, an expression.
- lncollect(expr) returns
expr with the logarithms collected.
It may be a good idea to factor the expression with factor
before collecting by lncollect).
Examples
| lncollect(ln(x+1)+ln(x-1)) |
|
| |
ln | ⎛
⎝ | ⎛
⎝ | x+1 | ⎞
⎠ | ⎛
⎝ | x−1 | ⎞
⎠ | ⎞
⎠ |
| | | | | | | | | | |
|
| lncollect(exp(ln(x+1)+ln(x-1))) |
Remark.
Note that, for Xcas, log is the natural logarithm, the same as
ln; for the base 10 logarithm, use log10.