The statement above should indicate all prime numbers between 3 and 20. When x is prime, y should be 1, yet y is always zero.....Is this a bug? Can logical operations be plotted?
Here is a more simplified example..
This should be 1 at x = 5 and zero elsewhere...but it's zero everywhere!!!
Here is another example, in case it's an issue of the plotting function never exactly hitting the value of 5.
This one should be one when x lies between 4 and 6 and zero elsewhere. Instead it's one everywhere.