I get error message <string>: 149: RuntimeWarning: invalid value encountered in sqrt when generating a list

Question

def ellipse(numPoints, genX=np.linspace, HALF_WIDTH=10, HALF_HEIGHT=6.5): xs = 10.*genX(-1,1,numPoints) ys = 6.5*np.sqrt(1-(xs**2)) return(xs, ys, "-") 

I am getting an error indicating an invalid value in squareroot. I don’t understand what it is.

 sqrt(0) = 0 6.5*sqrt(1- (-1**2)) = 0 

They should work, but y values ​​have problems, they return "nan"

Answer 1

maybe xs**2 returns a number > 1 sqrt with a negative number will return nan (not a number)

 >>> import numpy as np >>> np.sqrt(-1) nan 

If I correctly numpy provides complex number functions, which I think is the only way to represent sqrt (x), where x <0