Mathematical symbol to express monotonic relation between variables

Question

I wonder if there exists a symbol with which we could express that a variable $y=y(x)$ is monotonic with respect to $x$. In a similar way that the $\propto$ symbol expresses proportionality but in a wider sense, without requiring a linear dependence.

Answer 1

If it is just to write class notes, you could use $\nearrow$ for a monotonically increasing function and $\searrow$ for a monotonically decreasing function.