Desmos Graph

What math sequence did you used to make this?

\left\{\left|x\right|\le\sqrt{2}+1:\left(\left|x\right|-1\right)^{2},\sqrt{2}\le\left|x\right|:\left[-2,2\right]\sqrt{1-.25\left(\left|x\right|-\sqrt{2}-4\right)^{2}}+2\right\}

That sounds like a fnf mod to me with all the left right left right left right