why does the use of j (imaginary) generates a list of incremental values

Asked Jul 04 '17 at 12:36

Active Jul 04 '17 at 13:01

Viewed 158 times

I have the following code :

def sphere():
    #helper function to compute the coordinates of a unit sphere centered at 0,0,0
    # Create a sphere
    r = 1
    pi = np.pi
    cos = np.cos
    sin = np.sin
    phi, theta = np.mgrid[0.0:pi:20j, 0.0:2.0 * pi:20j]
    x = r * sin(phi) * cos(theta)
    y = r * sin(phi) * sin(theta)
    z = r * cos(phi)
    return (x,y,z)

The code works fine but I don't understand the part where 0.0:2.0 * pi:20j obviously, it makes 20 subdivisions between 0 and 2pi but why?

what's the connection between the complex number and the generated list?

edited Jul 04 '17 at 13:01

asked Jul 04 '17 at 12:36

itzik Ben Shabat

yes, `j`-literal denotes an imaginary number – Zinki Jul 04 '17 at 12:37
2

Actually it is an *imaginary* number. – zmbq Jul 04 '17 at 12:38
@zmbq yes good point. `20j` is an imaginary number, `1+20j` is a complex number. – Zinki Jul 04 '17 at 12:40
@Zinki but this doesnt answer the question. I asked how come it generates a list of numbers in the interval, I changed the title and the question to clarify what i dont understand – itzik Ben Shabat Jul 04 '17 at 12:58
The answer is [right there in the docs](https://docs.scipy.org/doc/numpy/reference/generated/numpy.mgrid.html). – Nils Werner Jul 04 '17 at 13:03
@NilsWerner Thanks! I thought it was a python thing, but now I see its a np.meshgrid thing. – itzik Ben Shabat Jul 04 '17 at 13:11

why does the use of j (imaginary) generates a list of incremental values

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