If z = e {\displaystyle z=e} then
e = e x 2 + 4 y 2 {\displaystyle e=e^{x^{2}+4y^{2}}} and by taking the logarithm of both sides:
This is an ellipse.
The four easiest points are the intercepts.
If x = 0 {\displaystyle x=0} then 4 y 2 = 1 {\displaystyle 4y^{2}=1} and y = ± 1 / 2 {\displaystyle y=\pm 1/2} are the y-intercepts. If y = 0 {\displaystyle y=0} then x 2 = 1 {\displaystyle x^{2}=1} and x = ± 1 {\displaystyle x=\pm 1} are the x-intercepts. The sketch is below: