Mandelbrot set

The Mandelbrot set is a two-dimensional <a href="/facts/Set_(mathematics)/BfucfHMq">set</a> that is defined in the <a href="/facts/Complex_plane/vE0QrxJp">complex plane</a> as the <a href="/facts/Complex_number/2w7mqI7e">complex numbers</a> 
 
 
 
 c
 
 
 {\displaystyle c}
 
 for which the function 
 
 
 
 
 f
 
 c
 
 
 (
 z
 )
 =
 
 z
 
 2
 
 
 +
 c
 
 
 {\displaystyle f_{c}(z)=z^{2}+c}
 
 does not <a href="/facts/Stability_theory/Su5sHnxs">diverge</a> to infinity when <a href="/facts/Iteration/AMc1p7BL">iterated</a> starting at 
 
 
 
 z
 =
 0
 
 
 {\displaystyle z=0}
 
, i.e., for which the sequence 
 
 
 
 
 f
 
 c
 
 
 (
 0
 )
 
 
 {\displaystyle f_{c}(0)}
 
, 
 
 
 
 
 f
 
 c
 
 
 (
 
 f
 
 c
 
 
 (
 0
 )
 )
 
 
 {\displaystyle f_{c}(f_{c}(0))}
 
, etc., remains bounded in <a href="/facts/Absolute_value/dwJBpEs5">absolute value</a>.
This set was first defined and drawn by <a href="/facts/Robert_W._Brooks/XfRkBr67">Robert W. Brooks</a> and Peter Matelski in 1978, as part of a study of <a href="/facts/Kleinian_group/FBMCx9Ry">Kleinian groups</a>. Afterwards, in 1980, <a href="/facts/Benoit_Mandelbrot/fa8tKP93">Benoit Mandelbrot</a> obtained high-quality visualizations of the set while working at <a href="/facts/IBM/QszA7nwd">IBM</a>'s <a href="/facts/Thomas_J._Watson_Research_Center/XfGnAzRW">Thomas J. Watson Research Center</a> in <a href="/facts/Yorktown_Heights%2c_New_York/koTowxzF">Yorktown Heights, New York</a>.

Images of the Mandelbrot set exhibit an infinitely complicated <a href="/facts/Boundary_(topology)/WgdH18kp">boundary</a> that reveals progressively ever-finer <a href="/facts/Recursion/CxSKxJoW">recursive</a> detail at increasing magnifications; mathematically, the boundary of the Mandelbrot set is a <a href="/facts/Fractal_curve/jjanzwda">fractal curve</a>. The "style" of this recursive detail depends on the region of the set boundary being examined. Mandelbrot set images may be created by sampling the complex numbers and testing, for each sample point 
 
 
 
 c
 
 
 {\displaystyle c}
 
, whether the sequence 
 
 
 
 
 f
 
 c
 
 
 (
 0
 )
 ,
 
 f
 
 c
 
 
 (
 
 f
 
 c
 
 
 (
 0
 )
 )
 ,
 …
 
 
 {\displaystyle f_{c}(0),f_{c}(f_{c}(0)),\dotsc }
 
 <a href="/facts/Sequence/gV2S4uqp">goes to infinity</a>.[close paraphrasing] Treating the <a href="/facts/Real_numbers/R02gw5Pb">real</a> and <a href="/facts/Imaginary_number/6Xh9W3hq">imaginary parts</a> of 
 
 
 
 c
 
 
 {\displaystyle c}
 
 as <a href="/facts/Image_coordinate/Mtd0q4SP">image coordinates</a> on the <a href="/facts/Complex_plane/vE0QrxJp">complex plane</a>, pixels may then be colored according to how soon the sequence 
 
 
 
 
 |
 
 
 f
 
 c
 
 
 (
 0
 )
 
 |
 
 ,
 
 |
 
 
 f
 
 c
 
 
 (
 
 f
 
 c
 
 
 (
 0
 )
 )
 
 |
 
 ,
 …
 
 
 {\displaystyle |f_{c}(0)|,|f_{c}(f_{c}(0))|,\dotsc }
 
 crosses an arbitrarily chosen threshold (the threshold must be at least 2, as −2 is the complex number with the largest magnitude within the set, but otherwise the threshold is arbitrary).[close paraphrasing] If 
 
 
 
 c
 
 
 {\displaystyle c}
 
 is held constant and the initial value of 
 
 
 
 z
 
 
 {\displaystyle z}
 
 is varied instead, the corresponding <a href="/facts/Julia_set/dmn8xIcG">Julia set</a> for the point 
 
 
 
 c
 
 
 {\displaystyle c}
 
 is obtained.
The Mandelbrot set is well-known, even outside mathematics, for how it exhibits complex fractal structures when visualized and magnified, despite having a relatively simple definition.

Mandelbrot set open-in-new

Mandelbrot set