The inverse function of the function $\mathrm{f}\left(\mathrm{x}\right)=\mathrm{f}\left(\mathrm{x}\right)=\frac{{\mathrm{e}}^{\mathrm{x}}-{\mathrm{e}}^{-\mathrm{x}}}{{\mathrm{e}}^{\mathrm{x}}+{\mathrm{e}}^{-\mathrm{x}}}$ is:

Let $\left\{x\right\}$ and $\left[x\right]$ denote the fractional and integral part of a real number $x$ respectively. Then the solution set of $4\left\{x\right\}=x+\left[x\right]$