What is LN in the formula?

Question

From this website I got the formala to calculate the Dewpoint , http://bmcnoldy.rsmas.miami.edu/Humidity.html?fbclid=IwAR1jTsCLwflvqwW0XH7RU48-GGasTOfkKpxacv8CFfJ8O6OullLD2Pg7cPM

and formula for which shown on the link above is

TD =243.04*(LN(RH/100)+((17.625*T)/(243.04+T)))/(17.625-LN(RH/100)-((17.625*T)/(243.04+T)))

I want to know what is LN ? I want to plug this formula to my sql for other purpose !

Answer 1

LN is the MySQL function for the natural logarith: the value of $x$ to which $e$ would have to be raised such that $e^x=y$ is denoted as $x=\ln(y)$, or equivalently, $x = \log_e(y)$.

Answer 2

It is the natural logarithm. You should have that as a function in whatever software you are using. As $\frac {RH}{100}$ will be between $0$ and $1$ the log will be negative.