when I use php function ,like ln() log()、exp(), in $formula with bc::parse(), it output a string for me. also in pow(x,y) <bountysource-plugin> --- Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/49034317-support-log-exp-function?utm_campaign=plugin&utm_content=tracker%2F31066270&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F31066270&utm_medium=issues&utm_source=github). </bountysource-plugin>