A Nomogram for the Incomplete $\Gamma$-Function and the $\chi^2$ Probability Function

A nomogram is constructed of the function $P(\chi^2,n)=1-\Gamma(m,y)$. For $n\geq30$ the function $\Pi$ is introduced, which is obtained from $P$ by means of the transformation $t=\sqrt{2\chi^2}-\sqrt{2n},x=\sqrt{2/n}$, while for $1\leq n\leq30$ the function $P$ itself is considered.
The nomogram is valid for the following values of $n,t,\chi^2$ and $P$: $1\leq n\leq\infty$; $|t|\leq3.1$; $1\leq\chi^2\leq30$; $0.001\leq P\leq0.999$. The absolute error in the entire nomogram for $0.01\leq P\leq0.99$ is found not to exceed $0.005$.