Stereographic Projection of z and 1/z Reflections in Reimann Sphere

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In summary, the stereographic projections of the points z and 1/\overline{z} are reflections of each other in the equatorial plane of the Riemann sphere. The magnitude of 1/\overline{z} is 1/(x^2 + y^2), and its projection is x_{2} = 2x(x^2 + y^2)/(1 + (x^2 + y^2)). This is different from the previous calculation due to a sign error. Therefore, the two projections are reflections of each other.
  • #1
stunner5000pt
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Show that the stereographic projections of the points z and [itex] 1/\overline{z} [/itex] are reflections of each other in teh equatorial plane of the Reimann sphere

ok so let z = x + iy
then [tex] \frac{1}{\overline{z}} = \frac{x - iy}{x^2 + y^2} [/tex]
so the magnitude of [tex] \frac{1}{\overline{z}} [/tex] is [tex] \frac{1}{x^2 + y^2} [/tex]

the stereogrpahic projection of z is
[tex] x_{1} = \frac{2x}{x^2 + y^2 +1} [/tex]
[tex] y_{1} = \frac{2y}{x^2 + y^2 +1} [/tex]
[tex] z_{1} = \frac{x^2 + y^2 -1}{x^2 + y^2 +1} [/tex]

for 1/ z bar is
[tex] x_{2} = \frac{2x(x^2 + y^2)^2}{1 + (x^2 + y^2)^2} [/tex]
[tex] y_{2} = \frac{2y(x^2 + y^2)^2}{1 + (x^2 + y^2)^2} [/tex]
[tex] z_{2} = \frac{1-(x^2 + y^2)^2}{1 + (x^2 + y^2)^2} [/tex]
i fail to see how these are reflections of each other, then shouldn't the x1 = - x2?? and so on??

please help!
 
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  • #2
stunner5000pt said:
so the magnitude of [tex] \frac{1}{\overline{z}} [/tex] is [tex] \frac{1}{x^2 + y^2} [/tex]
You sure about that?
 
  • #3
assyrian_77 said:
You sure about that?
perhaps I am missing something here??
 
  • #4
stunner5000pt said:
perhaps I am missing something here??
Well, the magnitude of a complex number [itex]z=x\pm iy[/itex] is [itex]|z|=\sqrt{x^2+y^2}[/itex], but you probably know this already. You have the complex number

[tex]\frac{1}{\overline{z}}=\frac{x-iy}{x^2+y^2}=\frac{x}{x^2+y^2}-i\frac{y}{x^2+y^2}[/tex]

I get a different magnitude than yours.
 
  • #5
ys i got what u got ( i made a sign error)

so the magnitude would be...
[tex] \sqrt{\left(\frac{x}{x^2 + y^2}\right)^2 +\left(\frac{y}{x^2 + y^2}\right)^2} = \sqrt{\frac{1}{x^2 + y^2}} [/tex]

the projection is then

[tex] x_{2} = \frac{2x(x^2 + y^2)}{1 + (x^2 + y^2)} [/tex]

right?
i know sily math errors everywhere!
 
  • #6
is what i did in the above post correct now??
 

1. What is Stereographic Projection?

Stereographic Projection is a method for representing points on a 3-dimensional sphere onto a 2-dimensional plane. It involves projecting the points from the surface of the sphere onto a plane that is tangent to the sphere at one of its poles.

2. How does Stereographic Projection work on the Reimann Sphere?

The Reimann Sphere is a way of visualizing the complex plane as a sphere, with the north pole representing infinity and the south pole representing zero. Stereographic Projection on the Reimann Sphere involves projecting points on the complex plane onto the sphere, and then projecting those points from the sphere onto a plane tangent to the sphere at the north pole.

3. What are z and 1/z Reflections?

z and 1/z Reflections are transformations of points on the complex plane. A z Reflection reflects a point across the real axis, while a 1/z Reflection reflects a point across the unit circle centered at the origin.

4. How are z and 1/z Reflections represented on the Reimann Sphere?

Z and 1/z Reflections can be represented as rotations on the Reimann Sphere, where the rotation angle is equal to the argument of the complex number being reflected. The rotation axis passes through the north and south poles of the sphere.

5. What are the applications of Stereographic Projection of z and 1/z Reflections in Reimann Sphere?

Stereographic Projection of z and 1/z Reflections on the Reimann Sphere is commonly used in complex analysis and geometry. It can also be used in the visualization of complex functions and their transformations. Additionally, it has applications in computer graphics and mapping techniques.

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