I made a square plot using $(x^{16}+y^{16})^{1/32}$ like below,and now I want make a isosceles trapezoid or just move center's square more upper, just like standing in a cave,triangle at bottom should bigger than top's triangle ,sorry for my bad English .so how to plot it using math formula,how to solve this ? thank you !
You could try $((x-y)^{16}+y^{16})^{1/32}$.
How about $\left(x(\frac{3}{2}-\frac{1}{2}y)\right)^{16}+y^{16}$ ?
EDIT: If you want it with the wider part on the bottom, just use $\left(x(\frac{3}{2}+\frac{1}{2}y)\right)^{16}+y^{16}$.
Perhaps you mean something like $$\eqalign{ \left( \left( 5\,y+2\,{x}^{2}+2\,{y}^{2}+2 \right) ^{32}\right. &+ \left( -5 \,y+2\,{x}^{2}+2\,{y}^{2}+2 \right) ^{32}\cr+ \left( -4\,x+y+2\,{x}^{2}+2 \,{y}^{2}+2 \right) ^{32}&+ \left.\left( 4\,x+y+2\,{x}^{2}+2\,{y}^{2}+2 \right) ^{32} \right) ^{1/32}\cr&-2\,{x}^{2}-2\,{y}^{2}-2 }$$
